I'll throw a few out there that haven't been mentioned:
This Alien Shore by C.S. Friedman
Nightfall by Isaac Asimov and Robert Silverberg
Darwin's Radio by Greg Bear
Darwin's Children (sequel) by Greg Bear
(Links got to Wikipedia articles for the books).
My boyfriend wants me to add Neuromancer by William Gibson, Snow Crash by Neal Stephenson, and Earth by David Brin, but I can't vouch for them directly.
