The Harry Potter series (looking forward to
The Order of the Phoenix).
The Lord of the Rings series.
Ender's Game is one of my favorite books of all time. I just love it oh-so-very much.
Just started reading
Cryptonomicon, by Neal Stephenson (I've heard he's on par with William Gibson with his writing, but, as opposed to Gibson, he actually knows a thing or two about computers, which is probably beneficial when you're writing cyberpunk). It's pretty good, so far (given, that's 25 pages, or so, out of around 1200

)
Just finished
Contact, by Carl Sagan. Very cool book... except for the very end. Oh well.
For having a room full of books, I'm drawing a blank as to my favorites...
I can highly recommend
Survivor, by Chuck Palahniuk (author of
Fight Club, but in that case, the movie was a lot better than the book, imho).
Siddhartha, by Hermann Hesse, comes to mind, along with
Fahrenheit 451, by Ray Bradbury.