Great call - Replay is one of my all-time favourites.
I'm also just re-reading another favourite, A Fire Upon the Deep by Vernor Vinge.
Some of my other favourites:
Practically anything by Neal Asher or Alastair Reynolds
Dune - Frank Herbert
Hyperion - Dan Simmons
The Forever War - Joe Haldeman
The Stars My Destination - Alfred Bester
The Anubis Gates - Tim Powers
I Am Legend - Richard Matheson
The Kraken Wakes/The Day of the Triffids/The Midwich Cuckoos - John Wyndham
The Time Machine/The Island of Doctor Moreau/The War of the Worlds - H. G. Wells
The Night's Dawn Trilogy - Peter F. Hamilton
Feersum Endjinn/The Player of Games/The Algebraist/Against A Dark Background/Use of Weapons - Iain M. Banks
Voyage - Stephen Baxter
The Milkweed Tryptich - Ian Tregillis
Lord of Light - Roger Zelazny
I'm sure I'll come up with loads more after I post this . . .