Favorite popular math book Christmas is almost here, so imagine you want to buy a good popular math book for your aunt (or whoever you want). Which book would you buy or recommend?
It would be nice if you could answer in the following way:
Title: The Poincaré Conjecture: In Search of the Shape of the Universe
Author: Donal O'Shea 
Short description: The history of the Poincaré Conjecture.
(Perhaps something like "difficulty level": + (no prior knowledge of math, as the book mentioned above), ++ (some prior knowledge of math is helpful), +++ (Roger Penrose: Road to Reality (?))
I hope this is appropriate for MO, since I think is of interest to mathematicians (at least for those who want to buy a popular math book for some aunt :-) ).
 A: Title: An Imaginary Tale
Author: Paul Nahin
Short Description: This book is primarily about complex numbers.  I can't remember it that well, but most of the book doesn't require calculus (though a fair part definitely does).    Most of it is about the algebra and geometry of complex numbers and is thus accessible to the nonmathematician.  The last chapter has a very fun introduction to complex analysis.
A: Wonder why it is that nobody has mentioned Lion-Hunting & Other Mathematical Pursuits? That book is one of my all-time favorites.
The book was edited by Gerald L. Alexanderson, the same individual behind the random walks of G. Pólya. Not only does the book contain the original article that launched the theory of big game hunting as a branch of mathematical research of its own, but also several of the subsequent contributions motivated by that 1938 groundbreaking paper of H. Pétard, e.g.:


*

*If there is an even number of lions in the Sahara Desert we add a tame lion. Thus we may assume that the group of the Sahara lions is of odd order. This renders the situation capable of solution according to the work of Feit and Thompson.

A: What about the Princeton Companion to Mathematics? 
It contains alot of introductory information on the spectrum 
of mathematics with historical note. When you need a quick
perspective on branches of mathematics that are less familiar
to you, it is a place to go. The book is divided into sections
on famous mathematicians, theorems, and branches of mathematics
all of which cannot be held by even the most well versed
mathematician. 
A: Title: The Art of Mathematics
Author: B. Bollobas
Short Review: "The Author considers these problems to be the type that two mathematical friends would pose to each other and discuss over a cup of coffee in a lounge. I agree with that premise, they are not too hard and there is a proof that is relatively easy to discover and even easier to understand. These problems satisfy all of the requirements for a good problem..."
This is one of the most entertaining recreation-mathematical books I've ever read. It does require some mathematical knowledge to be fully appreciated though :)
A: Title: A tangled tale
Author: Lewis Carroll
Description: (by Carroll himself in the preface) The writer’s intention was to embody in each Knot (like medicine so dexterously, but ineffectually, concealed in the jam of our early childhood) one or more mathematical questions — in Arithmetic, Algebra, or Geometry, as the case might be — for the amusement, and possible edification, of the fair readers of that magazine.
Of course, this will work as a gift for a niece better than a gift for an aunt, but it is one of those few books (the only other ones I know are by Smullyan and they've been mentioned already) that have both an entertaining story line and some actual mathematical challenges for the reader in them and that require no special mathematical training to read and enjoy. 
A: Title: Hilbert
Author: Constance Reid
Description: Biography of David Hilbert. Fascinating. Don't have to be D.H. to enjoy it. [the following is added from a duplicate answer - feel free to clean up -- ed.] A beautiful biography of a famous mathematician, showing the passion for knowledge represented by Hilbert and others at Goettingen around 1900. The book has a good description of Hilbert as a person, describes his family and coworkers and (sadly) the decay at the end of Hibert's life as the Nazis took over. I ask some of my undergraduate students to read this so that they can see the excitement of being in our profession. (The book is out of print, I think, but available via half.com or ebay.)
Second recommendation Also, Time-Life, ca. 1965, published one of it's picture books on math, titled of all things
Mathematics (as I recall). Check it out if you can find it. Lots of cool pictures. Great
for mathematically inclined high school kids.
Note added in edit:  The aforementioned book from the Time-Life series also had great
pictures of mathematicians. As I recall, there was one of Eilenberg lying on the couch
of his Grenwich Village apartment, coat and tie still on. It was captioned with a quote which
went, if I recall correctly, "Sometimes I like to think riding on the subway, but mostly I
like to think lying down." Absolutely formative in my personal approach to math!
A: Title:  Godel, Escher, Bach: an Eternal Golden Braid
Author:  Douglas Hofstadter
Short Description:  It's mildly debatable whether this is in fact a book about mathematics, but any mathematician who has read this book will understand why I recommend it and any who has not should.  Probably best for those with either a philosophical or musical bent.
A: Title: Flatland
Author: A. Square / Edwin A. Abbot
Short Description: Imagine how life would be in less than three dimensions.
A: Title: Logicomix: An epic search for truth
Authors:  Apostolos Doxiadis, Christos Papadimitriou
Artists: Alecos Papadatos, Annie Di Donna
Short description: A comic book biography of Bertrand Russell, focusing on his work on the foundation of mathematics. (About 345 pages. I just started reading it, so I haven't formed a firm opinion on it yet, but I like what I see so far.)
A: Title: Perfect Rigor: A Genius and the Mathematical Breakthrough of the Century
Author: Masha Gessen
Short Description: Story of Grigory Perelman based on information from people who interacted with him. A lot of interesting stuff about life in general and mathematics education in particular in Soviet Union around 1980's. There is only one or two short chapters where the author tries to explain the mathematics but if you skip those you don't need any serious mathematical skills.
A: Title: The Mathematician's Brain
Author: David Ruelle
Short description: (++) A book describing how Mathematics are founded, and tries to give a reasoning for the brain-work needed to do math. 
From Amazon: The Mathematician's Brain poses a provocative question about the world's most brilliant yet eccentric mathematical minds: were they brilliant because of their eccentricities or in spite of them? In this thought-provoking and entertaining book, David Ruelle, the well-known mathematical physicist who helped create chaos theory, gives us a rare insider's account of the celebrated mathematicians he has known-their quirks, oddities, personal tragedies, bad behavior, descents into madness, tragic ends, and the sublime, inexpressible beauty of their most breathtaking mathematical discoveries.
A: Title: Mathematics: A very short introduction
Author: Timothy Gowers
Short description: As the title says, very short. Gives the non-mathematical reader a good idea what mathematics is all about in just about 100 small pages.
A: Title : The Parrot's Theorem (Le théorème du perroquet)
Author : Denis Guedj
Description : I read this while in high school, it's kind of a murder mystery, and it revolves around a family who has a mathematician friend who was trying to solve the Goldbach conjecture and Fermat's last theorem before he died. It includes many fun mathematics and is presented in a very light to read manner.
A: Title: The Man Who Loved Only Numbers
Author: Paul Hoffman
Short Description: A biography of Paul Erdős. No previous knowledge of math.
A: Title: Recoltes et Semailles (Reapings and Sowings)
Author: Alexander Grothendieck
Description: Grothendieck's autobiography and self-assessment as a mathematician and a person.
A: I like Mario Livio's books:
The Golden Ratio: The Story of PHI, the World's Most Astonishing Number 
and
The Equation That Couldn't Be Solved: How Mathematical Genius Discovered the Language of Symmetry
A: Title: The Magical Maze
Author: Ian Stewart
Short description: Various bits of counterintuitive, fundamental, and/or easily understood mathematics, to wit: modular arithmetic, Fibonacci numbers, depth-first search, the axiomatic method, the Monty Hall problem, the birthday paradoxes, wallpaper groups, cellular automata, dynamical systems, formalism, Godel incompleteness, Turing's halting problem, optimization problems (both continuous and discrete), algorithmic complexity, fractals, chaos, and Hausdorff dimension.
This book is, to a large extent, the reason I am in graduate school right now. I read it in the eighth grade, and now here I am.
A: Title: Satan, Cantor & Infinity
Author: Raymond M. Smullyan
Short Description: Another gem in the list of Smullyan's books. If you love "logical sorcery", this is a perfect gift for you.
A: Title One Two Three . . . Infinity: Facts and Speculations of Science
Author George Gamow
Short description While not limited to mathematics, this is a great book which presents some subtle mathematical ideas in an intuitive non-technical way. I especially like the presentation of Cantor's infinite cardinality theory, which can be followed by anyone. Unfortunately, there are some mistakes. I seem to recall his presentation implicitly assumes the continuum hypothesis, but maybe he did that for clarity. It doesn't really detract from the book. 
A: I see many favorites here, but this one should be mentioned too:
MR1710978 (2000h:00002) Hugo Steinhaus. Mathematical snapshots. Translated from the Polish. With a preface by Morris Kline. Reprint of the third (1983) English edition. Dover Publications, Inc., Mineola, NY, 1999. vi+311 pp. ISBN: 0-486-40914-7
It was first published in 1939 ("Kalejdoskop matematyczny" in Polish).     
Here is the summary:
http://books.google.com/books?id=N63XpD1oJ6IC&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
Things like fair division or platonic bodies made accessible for an aunt and a niece alike (I actually gave my copy to my niece a few years ago).
A: "classic"
Title: Fermat's Enigma: The Epic Quest to Solve the World's Greatest Mathematical Problem (US)
Fermat's Last Theorem: The story of a riddle that confounded the world's greatest minds for 358 years (UK)
Author: Simon Singh
Short Description: The history of Fermat's Theorem, from the famous note "It is impossible to separate a cube into two cubes, or a fourth power into two fourth powers, or in general, any power higher than the second into two like powers. I have discovered a truly marvellous proof of this, which this margin is too narrow to contain." to the solution of the Taniyama-Shimura-Conjecture by Andrew Wiles.
By the way, the video Fermat's Last Theorem (1996) is based on the book.
A: Title:  A Mathematician's Apology
Author: G. H. Hardy
Short Description: In the style of Plato and Xenophon, G. H. Hardy offers a justification for pure mathematics.
A: Title: The Book of Numbers.
Author: John Conway and Richard Guy.
Short Description:  A beautifully illustrated book with all sorts of facts about all sorts of numbers.  The difficulty is variable throughout the book: parts are written at a + level, while other parts are closer to +++.
A: Title: Journey Through Genius
Author: William Dunham
Short Description: A fencepost history of mathematics.  For each highpoint it describes some fun history and then the actual math.  Examples of topics covered are Heron's formula for triangular area, Euler's evaluation of $\zeta(2)$ and Cantor's set theory.
A: Title: Fearless Symmetry
Authors: Avner Ash and Robert Gross
Short Description: Very much a +++ text, these guys actually got a pop-math account of Galois representation theory published! By far the most technically demanding pop-math book I've ever read, (and one that took me about three years to actually finish) it nonetheless makes for a compelling "non-technical" introduction to a beautiful subject.
A: Title:  Wonders of Numbers: Adventures in Mathematics, Mind, and Meaning
Author:  Clifford A. Pickover
Short Description:  A wonderful collection of historical anecdotes, mathematical trivia, and puzzles.  I would especially recommend this if you were shopping for a younger relative.
A: Title: Another Fine Math You've Got Me Into
Author: Ian Stewart.
Short Description:  Mathematical puzzle columns, (originally for the French version of Scientific American) some of which introduce interesting concepts from higher mathematics.  Ian Stewart has written a lot in this vein (as have others, e.g. Martin Gardner), but this book is my favorite and is one of the mathematically meatiest of them (in my opinion).
I'd say this is a ++.
A: I'd recomend "The Pea and the Sun, a mathematical paradox" which roughly explains the proof of Bannach-Tarski Theorem, which is a consequence of the axiom of choice and roughly says that you can break a pea in a finite number of pieces, tehn reassemble the pieces and get the sun 
A: My favourite books are:


*

*$\text{I want to be a Mathematician}$ by Paul Halmos.

*Problems for Mathematicians, young and old, by the same author.

*The Man who knew Infinity: : A Life of the Genius Ramanujan by Robert Kanigel.  Fanastatic book. Covers almost all of Ramanujan's life and work. Certainly a must read.
A: Title: Innumeracy: Mathematical Illiteracy and its Consequences
Author: John Allen Paulos, mathematician and well-known skeptic (in the good, modern sense of the word).
Short description: Paulos explains for the general public (and he does it fairly well) why it should understand a little more mathematics and know how to do Fermi calculations and educated probabilistic guesses. The dangers coming from pseudosciences are also highlighted, something very needed nowadays in my opinion.
Math level: +. Some chapters are not that easy to read without a mathematical background, more because of the great number of calculations and logic steps involved in the explanations than because of the math level of those per se.
Price: 9.89$ at Amazon.
A: Title: The Lady or the Tiger? 
Author: Raymond Smullyan
Short Description: If your aunt is young enough not to scorn the fairy-tales, this book is a charming collection of logic puzzles, presented under a guise of an entertaining story. The book presuppose no knowledge of mathematics (so difficulty is +), but it ends with a version of Godel's incompleteness theorem. Your aunt will be delighted! 
Remark: Other books by Smullyan are also great, and will relieve you from wondering of what to give to your aunt for the next few Christmases.
A: Title: Proofs and Refutations - The Logic of Mathematical Discovery
Author: Imre Lakatos
Short Description: A Plato-esque dialogue between a teacher and his students, aiming to discuss how mathematical discovery happens, how mathematical arguments take form and how mathematical knowledge arises. The discussion is based around the Euler-characteristic, starting off with a concrete conjecture about polyhedra, expanding into the result in full-blown generality through investigation, trial-and-error, the occasional side-track and creative injections as it happens in real life. The book is also sprinkled with mathematical in-jokes, and interesting historical facts about the result. This is a real gem that I keep on my bedside table. Probably at the higher end of the ++ spectrum. 
I'm not sure if I'd get the book for my aunt. It takes mathematical reasoning skills to get though the argument and an understanding of why the questions above are worth answering in the first place. I might get it for a philosophically inclined friend instead. 
A: Title: Letters to a Young Mathematician
Author: Ian Stewart
Description: A beautiful book in which Stewart tries to convey in the form of letters from a mathematician to his grand daughter what sort of things does the profession of mathematics involves. It is very interesting since the letters advance from the time in which the grand daughter is in high school up until she is a professional mathematician doing research. I would recommend it without a doubt.
From my own experience it has been really nice to come to this book at different times during the past years. I started college as an engineering student but on my third year I started taking courses from the mathematics program and I bought and read this book when I was just beginning. I had no real idea of what pure mathematics was all about (since I was used to the kind of calculus courses in which the emphasis is on computation rather than proving things) and this book gave me at least some perspective and a few hints of what may be ahead of me.
Just for the record, I ended up switching my major to mathematics. 
A: Title: Prime Obsession
Author: John Derbyshire
Short Description: A book about the Riemann Hypothesis. Its been a while since I read this book, but I remember it being well-written and fun to read. It is very accessible, explaining everything. I think half of the chapters have no math (just facts about Riemann's personal life and such), while the rest is avery gentle introduction to math ideas (like infinite series). 
http://www.amazon.com/Prime-Obsession-Bernhard-Greatest-Mathematics/dp/0452285259/ref=sr_1_2?ie=UTF8&s=books&qid=1260570418&sr=8-2
A: Title: Gamma : Exploring Euler's constant
Author : Julian Havil
Short description: Provides a fascinating history of a constant that doesn't get nearly as much attention as $e$ or $\pi$. Definitely has more math than most books intended for a general audience but I feel the book is accessible to those who persevere with it. And the reward is lots and lots of beautiful mathematics.
A: Title:  Euclid's Window
Author:  Leonard Mlodinow
Short Description:  A history of geometry of sorts.  It's very well-written and was one of my favorite math books growing up.  But you should read the Table of Contents to actually get an idea of what the book is about.
A: Title: Introduction to Mathematical Thinking: The Formation of Concepts in Modern Mathematics
Author: Friedrich Waismann
Short Description: This book, first published in 1936, gives an introduction to the philosophy of mathematics and the foundations of analysis. It shows how to construct number systems, some very elementary set theory and how to make differential calculus precise. The focus is on concepts. It includes a discussion of things like continuuous, nowhere differentiable functions and discusses why R and R2 are isomorphic as sets but not topologically. It even gives an very short and intuitive proof that R and R2 are not homeomorphic.
The philosophical discussion is, naturally, a litlle bit dated. It discusses formalism, logicism and intuitivism. The philosophy still makes for exciting historical reading. It is clear that this discussion was very lively when this book was written.
The level should youalify as ++, the book is demanding but can certainly be read before going to college.
A: I know this is a little late for Christmas, but nevertheless, I have a few (some of which have already been mentioned) books I've read that I've quite enjoyed.  For the sake of brevity, I'll let you search the titles on Amazon for reviews and better descriptions.
Title: Everything & More: A Compact History of Infinity
Author: David Foster Wallace
Title: The Mathematical Experience
Author(s): Philip J Davis & Reuben Hersh
Title: One, Two, Three...Infinity
Author: George Gamow
Title: Pi in the Sky
Author: John D. Barrow
Title: Prime Obsession: Bernhard Riemann and the Greatest Unsolved Problem in Mathematics
Author: John Derbyshire
Title: Strength in Numbers
Author: Sherman Stein
Title: e: The Story of a Number
Author: Eli Maor
Title: A History of Pi
Author: Petr Beckmann
Title: Nature's Numbers
Author: Ian Stewart
Title: Mathematics: The Science of Patterns
Author: Keith Devlin
Title: Zero: The Biography of a Dangerous Idea
Author: Charles Seife
Title: How to Enjoy Calculus
Author: Eli S. Pine
(Not really a "popular" book, per se', but still pretty good)
Title: How to Think About Weird Things
Author(s): Theodore Schick & Lewis Vaughn
(Not really about mathematics, but not so far out of the way that you wouldn't enjoy it if you also enjoy mathematics)
A: Title: The Mystery of the Aleph: Mathematics, the Kabbalah, and the Search for Infinity
Author: Amir D. Aczel
Short Description: Another book about the development of ideas about infinity.  The central character is Cantor, of course, but it also looks at people before, like Bolzano and Galileo, and afterwards, including Godel and Cohen for their work on CH.
I read this in high school, having just a little calculus background, and got a lot out of it.  It does try to work in the themes of "contemplation of infinity leads to insanity" and "infinity as religious insight" a bit, which might be drawbacks.  But when I read it for the first time, I remember laughing out loud at how amazing the ideas involving infinte cardinalites and AC were, so at least those are presented well.
A: Title: Prisoner's Dilemma 
Author: William Poundstone
Short description (from New York Times Book Review): The real originality of PRISONER'S DILEMMA lies in its colorful synthesis of logical material and historical and biographical narration [which] takes us in parallel lines through cold war history, strategic games of the nuclear age and the life of von Neumann . . . Lively, open and multifaceted.
Indeed, the book can be read as a whole or just by following one of those "parallel lines". Depending of the line you choose, the level of difficulty would be + or ++!
A: Title: Uncle Petros and Goldbach's Conjecture
Author: Apostolos Doxiadis
Short Description: It is a very fun novel based on the life of a fictional character who spends most of his live trying to prove Goldbach's conjecture. It talks about some other famous problems in math. This novel is fun for mathematicians and non-mathematicians. No knowledge of math is required. 
A: Title: The Symmetries of Things
Authors:  John Horton Conway, Heidi Burgiel, and Chaim Goodman-Strauss
Description:  The authors begin by introducing the general concept of geometric symmetry / regular tiling, and then pose the problem of classifying all possible symmetries of the plane.  They provide an elegant topological classification, and along the way introduce the notions of orbifold and classify the compact surfaces with boundary.  It's then easy enough to also classify the discrete symmetries of the sphere.  In part II, the authors introduce the notion abstract group, and classify the prime-order "color symmetries" of the plane, which are tiling patterns with different-colored tiles.  Part III consists of a discussion of higher-dimensional tilings, including the four-dimensional Archimedean solids.
Part I is suitable for an interested amateur with no specific prior knowledge.  Part II is at an advanced undergraduate level, although it does contain new results.  Part III, which is about half the book, is research level.  The book is printed in full-color.
A: Title: The Curious Incident of the Dog in the Night-Time.
Author: Mark Haddon.
Description: A mathematically gifted kid tries to solve the mystery of a dog murdered in the night-time. 
Remark: Although this isn't a math book per se, it actually does contain a lot of interesting and non-trivial mathematics.  Also, it's very well illustrated.  As a final selling point, you have to respect any book whose chapters are indexed by the primes.  
A: Title: Symmetry and the Monster
Author: Mark Ronan
Short Description: The history of the classification of finite simple groups. Reads like a good novel.
A: Title: The Mathematical Experience
Authors: Davis and Hirsh
Short Description: A really accessible and funny introduction to the philosophy of mathematics.  I think the description of the "ideal mathematician" is particularly hilarious.
A: Title: Indiscrete Thoughts
Author: Gian-Carlo Rota
Description: General discussion on Mathematics, Princeton of the fiftees, lives of Artin, Feller and of Rota's intimate friend Stanislaw Ulam; fantastic bedtime reading. Also includes philosophical flavour like '10 things I had been taught' type.
A: Title: The Code Book
Author: Simon Singh
Description: This is a popularized history of cryptography and cryptanalysis. It runs the range from shift-ciphers to modern public key cryptosystems and quantum key distribution. No prior knowledge of maths is necessary, but can be helpful.
It has been quite some time since I read this book, but I found it incredibly engaging at the time. I know it isn't strictly focused on mathematics, but I am surprised that no one else has mentioned it.
A: Title: What is mathematics?
Author: Herbert Robbins and Richard Courant
This book is a very nice introduction to mathematics, it covers basic number theory, analysis, algebra, geometry and topology.
I'am very surprised that i couldn't find it on this list already.
(from a duplicate answer - feel free to edit) This would be for someone who has some mathematical ability, and really wants to understand what math is. Courant goes through essentially all of mathematics, starting at a very elementary level, but getting to some very deep and important stuff. He often does real proofs, and doesn't dumb it down, but does explain things conceptually very well, including sometimes giving just ideas or justifications for really difficult things, like the prime number theorem. I use this when I teach our senior proof seminar, just to force the math majors to own a copy.
A: Title: The honors class: Hilbert's problems and their Solvers
Author: Ben Yandell
Short description: The title says it all. It gets dense at times, but it has an enormous range of topics and the biographies are very interesting. Probably a ++.
A: Title: Euler's Gem: The Polyhedron Formula and the Birth of Topology
Author: David S. Richeson
Short Description: V-E+F=2. Requires little (no?) preparation, but some willingness to think. I gave it to a few people who wanted to know more about what math really was (as opposed to adding longer and longer columns of numbers, as my mother believes), and those who made the investment of their time came away with a  much better understanding.
A: Title: What is the name of this book?
Author: Raymond Smullyan
Short description: Lots and lots of logical puzzles (the kind with people always telling the truth, people always lying, people who sometimes tell the truth and sometimes lie, etc.) It is really entertaining, and it serves well as an introduction to the logic of propositions.
A: Title: King of Infinite Space: Donald Coxeter, the Man Who Saved Geometry 
Author: Siobhan Roberts
Short Description: Biography of Coxeter. 
A: Title: Everything and More: A Compact History of Infinity
Author: David Foster Wallace
Short description: History of the idea of infinity, mostly leading up to Cantor's set theory ideas. It's been awhile since I've read this but I would say the mathematics is pretty decent for popular writing and the writing is really enjoyable if you like Wallace's style (and maddening if you can't stand him, I'm sure). This is the kind of math book you could get for someone who enjoys serious literature.
No prior knowledge is necessary, but the math-phobic could struggle.
A: Title:  Men of Mathematics
Author: E. T. Bell
Short Description:  Short biographies (~30?) of important mathematicians.  Excellent relations of the death of Archimedes, Galois' temper, Newton's eccentricities, &c.  Also try his (Edit: actually L. Hogben's) book Mathematics for the Millions.
A: Title: Mathematics and the Imagination
Authors: Edward Kasner and James Newman
Short Description: A number of chapters covering lots of subjects: counting numbers (including the coining of the word "googol"); $\pi$, $i$, and $e$; geometries, plane and "fancy" ("Lobachevsky's Eiffel Towers and Riemann's Holland Tunnels"); puzzles; paradoxes; chance and probability; topology ("rubber sheet geometry"); calculus. Very much in the spirit of Martin Gardner columns, but from before they existed (the book was originally published in 1940; Gardner began writing his columns in 1956).  You can see a preview at Google books.
Which also leads me to
Author: Martin Gardner
Title: Various
Short Description: A joy to read.
A: Ian Stewart is a very good mathematics popularizer and I understand why many of his books are in this list.  But I really don't understand why none of Martin Gardner's books are listed here (at the time I'm writing this).
My favorite Martin Gardner book (actually, an updated collection of Scientific American Mathematical Games columns) is The Colossal Book of Mathematics.  From the book's cover: "Number Theory, Algebra, Geometry, Probability, Topology, Game Theory, Infinity, and other topics of recreational mathematics."  I would say its difficulty level is "+".
A: Title: Why Beauty is Truth: A History of Symmetry
Author: Ian Stewart
Brief Description: Stewart surveys the history of symmetry in mathematics (from ancient times to present day). There is particular emphasis on the insolvability of the quintic, the invention of Galois theory, and its impact on modern mathematics.
A: Title: The Man Who Counted (translated from Portuguese)
Author: Malba Tahan
 Short description:  A mixture of Arabian Nights and a classical puzzlebook. The stories follow a brilliant youth who solves mathematical problems. A highly enjoyable read for anyone who likes oriental tales, and just the right combination of adventures and mathematics for all aunts and nephews out there without a mathematics degree.
Malba Tahan is a pen name of the Brazilian mathematician and writer Júlio César de Mello e Souza. The book was first published as O homem que calculava in 1949.
A: Title: The I Hate Mathematics! Book
Author: Marilyn Burns
Short Description: The google.books description is well written. A book for nonbelievers. I had this as a kid, and i remember its questions and pictures having an effect on me. How many sides does a banana have and how can 4 colours colour this map.  
A: Title: Mathematics: A Very Short Introduction 
Author: Timothy Gowers
Short description: "A marvellously lucid guide to the beauty and mystery of numbers"
This book is excellent for someone who wants to delve in to some basic, but interesting mathematics. It avoids very "popular mathematics" such as chaos theory and focuses in detail on "mundane" topics, such as dimension and estimation.
difficulty level: +
£4.73 on Amazon UK
A: You should not miss this book about algebra. 
Title: Unknown Quantity
Author: John Derbyshire
Not only it explains the rise of algebra since antiquity, it also helps the reader to gain an intuitive approach to think and apply algebra in suitable problems. Great reading experience.
