Did iceman say 'To Kill a Mockingbird?' Finally someone mentions a real book.
Books you shouldn't miss out on:
In Sci-fi, there's Dune by Frank Herbert and Ender's Game by Orson Scott Card. Emphasis on Ender's Game, but both are worth the read.
In Fantasy there is the Dresden Files by Jim Butcher, a good series. Blows Harry Potter out of the water. Not for kids, by the way.
In classics there are too many. Slaughterhouse Five by Kurt Vonnegut. Treasure Island by Stevenson. Grendel by John Gardener. Homer's Odyssey. Anything by Shakespeare, I own the complete works in addition to my two working scripts from plays this past spring and summer.
My favorite is probably Speaker for the Dead, the sequel to Ender's Game. Very different than it's predecessor, you have to be half-way intelligent in order to understand any of it, but the issues it raises about interactions with species from another planet are most intriguing.