Someone mentioned Revelation Space! 'Tis my favorite series.
In addition, try House of Leaves (just noticed it was already mentioned =D)and John Dies At The End. JDatE is funny, dark, and well written. Oh man, still one of my favorites.
As far as classics go, The Age of Innocence surprised me. Interesting, thoughtful, and a heartrendingly compelling ending. Candide and Canterbury Tales are both good too, with humor that translates well even now.
My other options have been listed already; Ender's Game, anything Douglas Adams, etc.
Happy reading!