So I've seen at least three Neal Stephenson threads, a Will Gibson, a Phil Dick, and Ender's Game. Some more recommendations on books I think most geeks should read:
Vernor Vinge - Rainbows End. Seriously, every geek should read this book. It's the best fiction on near future augmented reality that I've seen myself. Vinge's A Fire Upon the Deep is also outstanding, but much more "out there"; it's more entertaining than eye-opening. It does have one of the best alien perspectives I've read. Not just humans with bumpy foreheads, really *alien* aliens.
Charles Stross - Just about anything, really. His "Laundry Files" fantasy read like a cross-between H.P. Lovecraft, Douglas Adams, and Ian Fleming ("James Bond"). I know that sounds really weird, but it works. They're a riot. More serious and sciency are the "Eschaton" books -- Singularity Sky and sequels. Some of his works are available online for free, legally. Scratch Monkey for example.
John Scalzi - Old Man's War. I just finished this myself. The finish was weak but the ideas are a blast. As one reviewer put it, it's like Starship Troopers without the lectures.
Here's a few others I'm suspect will won't appeal as broadly, but I'll throw in 'cause I want to. It's my post.
C.S. Friedman - This Alien Shore. Space SF. Protagonist is a girl with cooperative multiple personalities; this is fascinatingly portrayed. Very good speculation on how direct brain interfaces might be realized. Lots of diverse human cultures. The real winner, though, is a human culture that values emotional differences and has social customs to let people interact across such boundaries. Introverted geeks (INTJ) will love this. Friedman packs a very high density of ideas into her books.
Corey Doctorow - Down and Out in the Magic Kingdom . Free content. An interesting take on a post-scarcity meritocracy. I think it's kind of nutty, but interesting. For the price, it's decent.