Snow Crash by Neal Stephenson. It's hard to pick from my favorite list of fiction novels, but Snow Crash is definitely at the top of any list. Not only did this book introduce me to the themes in cyberpunk, it was one of the first books I read that really upped the pace and got my heart-racing. To a degree, it reminded me of the importance of fiction, whereas I had previously mostly focused on non-fiction.
-- Oliver Charles