This is the place that I comment on books I liked, books I don't like, and books that otherwise struck my interest. The focus here is on mathematics construed broadly.
The Man Who Loved Only Numbers: The Story of Paul Erdős and the Search for Mathematical Truth, Hyperion: New York, 1998.
This is the story of Paul Erdős: his life and his work. Hoffman is not a mathematician, but does describe Erdős' discoveries, though in an accessible manner. The book is an excellent biography, and a passable introduction for the neophyte to the mysteries of number theory. For those interested in the details, the book has a bibliography, source notes, and a full index.
The Book of Numbers, Springer-Verlag New York, 1996.
Surreal Numbers, Addison-Wesley Publishing Company, 1974.
A Mathematical Introduction to Logic, Harcourt Academic Press, 1972.
Cryptonomicon, Avon Books, 1999