Nobody passed this one on to me, but I've seen it floating around and feel like answering it, so there.
Number of books I own: About 8-900 (most currently in storage, unfortunately). This used to grow a lot more rapidly, but I'm much more of a re-reader than a pioneer nowadays.
Last book I bought: Riemann's Zeta Function, by Harold M. Edwards. The subject matter is fairly explanatory, I'd think ...
Last book I read: See preceding, and before that it was The Geometry of Schemes, by David Eisenbud. I actually do read books on subjects other than mathematics, I swear; this is a statistical anomaly! (Any "Numb3rs" viewers out there?)
Five books that mean a lot to me: I've answered this before, so this time I'll try for a totally different list.
- Bertrand Russell, The History of Western Philosophy. A lot of it is either tendentious or simply outright wrong, but to a 12 year old, this book was a revelation.
- Friedrich Nietzsche, Walter Kaufmann (trans.), The Portable Nietzsche. I picked this one up at the age of 17 in a bookstore on Tottenham Court Road. It led me to start thinking beyond good and evil as commonly understood, to a re-evaluation of all values, to the need to choose one's own reasons for being, rather than living by the words of some guru. After reading the real thing, Ayn Rand can't help but seem a pale imitation.
- Walter Rudin, Principles of Mathematical Analysis. Another acquisition I made about the time I bought the preceding item. This book may be panned by some for being too "slick" and abstruse, but it was my first introduction to what real mathematics was all about; Dedekind cuts, field axioms, countable vs. uncountable sets, Cauchy sequences, differential forms, even a little measure theory. To someone who's spent innumerable hours going through the typical calculus drill expected of high school students, it felt like being suddenly asked to man the controls of a fighter jet, scary as hell but exhilarating too.
- Franz Kafka, The Trial. Although I like the story Metamorphosis a great deal, The Trial gave me a much more complete immersion into the claustrophobic and absurd universe of Kafka's imagination. The feeling imparted by the book that life was arbitrary and ridiculous was one I could and still do identify with to a large extent, which is why Nietzsche's message resonated all the more with me.
- Rudiger Dornbusch, Macroeconomics. I actually read a much older edition of this book, and I don't recall Stanley Fisher as being a co-author of that one. At any rate, it inoculated me for life against all calls for protectionism, and thanks to it I arrived in college a die-hard free-trader who couldn't help but look on "anti-globalization" advocates as just a little brain-dead.
All right, that's my list all wrapped up. I guess it's at this point that I pass on the baton, so I nominate Frank McGahon, Radek, Dsquared and anyone else who's interested to give it a go.