Currently Online 
Hm. That's kind of tough.
Catch 22 - Pure brilliance.
Neuromancer
The Many Colored Land series - Very unique and creative sci-fi/fantasy hybrid.
Hyperion series
The Doomsday Book - Amazing book about a time-traveling researcher who gets stuck in the horrors of the Black Plague period of Europe by accident.
Clan of the Cave Bear series - The first book was remarkable.
Dune series
The Mirror of Her Dreams and A Man Rides Through
The Real Story and the rest of the Gap series
The Riftwar Saga series - The original series was awesome, some of the best fantasy I've ever read.
Dragonsong and Dragonsinger
The Observations
The Left Hand of Darkness
Skinny Legs and All
Watership Down
The Forgotten Beasts of Eld and pretty much anything else from Patricia McKillip
