This is copied from another thread, but it lists a lot of my thoughts and favorites, I've edited it a bit to make more sense:
I just read Song of Kali by Dan Simmons, that one is pretty remarkable. The Diamond Age by Neal Stephonson. I'm into his critically acclaimed Cryptonomicon. It's pretty great so far, but a huge read, and you really have to be a math major to totally enjoy it.
Terry Goodkind and Robert Jordan - so derivative of Tolkien it makes it hard for me to form an interesting opinion, but I hated them. For original, strong fantasy try Ursula Le Guin and the Wizard of Earthsea books or the two Mythago Wood books by Robert Holdstock (these two only if you have an interest in mythology). Also, The Song of Ice and Fire series beginning with A Game of Thrones by George RR Martein is an incredibly entertaining read if you don't mind a lot of sex, violence, politics, and jumping povs. I'd recommend Song of Ice and Fire to anyone.
Stephen King - He is amazing and you should try any of his popular ones for some good horror, but most of his books are pretty formulaic. An excellent novelist but don't limit yourself to one author. I should state I'm almost finished with the first of the Dark Tower series and can't wait to continue. Lovecraft is the perfect place to start for horror. The short stories are great. A Shadow Over Innsmouth (is that a novella more than a short story? and the Colour out of Space are my favorites).
Jim Butcher and the Dresden books for some fun magical mysteries. Also consider the Prey series by John Sandford if you like the mystery and a cool protagonist, or John Scalzi and the Old Man's War books if you like the fairly light SF. These are all great easy to read gems.
If you do like distopian/speculative fiction/commentary on society and where it's going-type books, be sure to check out Fahrenheit 451, Brave New World, 1984, Animal Farm, and Margaret Atwood (in particular The Handmaid's Tale, though Oryx and Crake and The Blind Assassin are good too).
As far as standard high school English class reads (I'm looking at you 1984) - keep reading past those. They're a great base, but more contemporary books are important too. There's a whole world of literature out there that's very worth your time. Sample from different genres too, don't get stuck.
Edit - I should also mention Douglas Adams and Terry Pratchett for some excellent humor books that remain great novels more than just a collection of jokes.