"Must read" papers in algebraic K-theory? I'm mainly interested (graduate student) in surgery theory and geometric topology.
If I have a chance to suggest "must read" papers in geometric topology for beginner, 
I'm very glad to suggest "Topological Library" books volume 1,2,3
(including monumental papers of Smale,Milnor,Kervaire-Milnor,Thom,Serre,Novikov...) 
available in the following cite.(volume 3 is not available in English edition up to now)
http://www.amazon.com/Topological-Library-Characteristic-Structures-Everything/dp/9812836861/ref=sr_1_1?s=books&ie=UTF8&qid=1296894607&sr=1-1
Question: What are "must read" papers in algebraic K-theory?
(I hope that most of them can be readable with basic understanding about classical K-theory such as Rosenberg's text or Milnor's ann. math. studies book)
 A: The first few sections of the Thomason/Trobaugh paper constitute an exceptionally readable overview of the Waldhausen approach to K-theory, with very few prerequisites.  
A: Quillen's "Higher Algebraic K-Theory I" is probably the best source for understanding the basics and the original intuition.
Thomason/Trobaugh is also an excellent paper, but it is a fairly large paper and very fundamental (so the first half of the paper is dedicated to construction of the basic objects).
And if you want a deeper understanding, you could have a look at some of Thomason's older papers, as well as some of Waldhausen's papers.
When I was learning Algebraic K-Theory, I kind of found it easier to understand by going backwards (i.e. I would think of something to get a kind of big picture, ask myself questions about why something might be true, and use that approach to go backwards through Thomason/Trobaugh and if necessary back to older papers).  Not everyone will agree with this approach, but I felt that it helped me to build the intuition needed to progress in the subject.
A: On the Lichtenbaum-Quillen Conjectures from a Stable Homotopy-Theoretic Viewpoint by Stephen A. Mitchell (around 60 pages) contains unbelievable amount of the very key information on both algebraic K-theory, stable homotopy theory, and their most exciting interactions. When I started reading it, I thought I knew some of both, and was overwhelmed by the breathtaking panorama the author was skillfully presenting, showing only the very essence and at the same time managing to convey deepness and importance of several highly technical methods. Fantastic paper!
A: I'd say, of course Quillen's "Higher algebraic K-theory I", the "K-theory Handbook".
A: Algebraic K-theory of spaces by Friedhelm Waldhausen.
