1. A Song of Ice And Fire by George R. R. Martin - 5th book to be released on July 12th, first book made into series called Game of Thrones (selftitled) by HBO. Simply the best fatasy novels you can read. I know of only one book that can fight for the first spot, and that is...
2. Malazan Book of the Fallen by Steven Erikson - pure and epic briliance, from what i know, it hasn't been made into a film or tv series yet, but once it does, oh my gosh ;p very good and very long read, totally worth it
3. Ender's Game by Orson Scott Card - the best Sci-Fi book you can get, hands down. Oh, and it's on the FBI's list ... so if you're thinking of joining the academy, you should read this alongside The Art of War by Sun Tzu ;-)
4. Foundation series by Isaac Asimov - this guy was genius! Thrilling read from start till the end, a must read for sci-fi fans!
5. The Girl With The Dragon Tattoo or Millenium series by Stieg Larsson - great criminal story with a heroin that is, in my opinion, the best female character ever put on paper.
6. Many many more novels out there that are worth reading.