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 :)