Total number of books I've owned: Somewhere north of 1200, I think. There are (at a rough estimate) about 800 on the shelves in my library right now, another 100 or so in boxes, then there are the bookshelves in my office, the books still at my parents' house, and the ones given away along the way.
The last book I bought:Kushiel's Dart, Jacqueline Carey.
The last book I read: Let's see. Last book I finished: Pattern Recognition, William Gibson. Currently in progress: Raising the Stones, Sheri Tepper.
5 books that mean a lot to me:
Godel, Escher, Bach, Douglas Hofstadter
The Sandman, Neil Gaiman. If I have to choose a single volume I'll go for The Wake.
Griffin and Sabine, Nick Bantock. Again, if I have to choose one... the first one, I suppose.