Alistaire Reynolds "Revelation Space" (must read from the beginning)
The early Honor Harrington stories by David Weber.
Peter Hamilton's Reality Disfunction series. Peter Hamilton's Pandora's Star series.
David Feintuch's Hope series. (first 4 books)
Heinlein
Forward
Niven
Pournelle
Joe Haldeman
Keith Laumer's time travel and alternate-universe stories.
Iain Banks "Culture" novels
Greg Bear (Eon, Queen of Angels)
Neil Gaiman (American Gods, Good Omens-with Terry Prattchet).
Vernor Vinge (everything),
Dan Simmons (Hyperion Cantos)
Neal Stephenson (Diamond Age; Snow Crash; CRYPTONOMICON)
Orson Scott Card
Fred Hoyle's "Black Cloud"
Willam Gibson "Neuromancer"
Phillip K. Dick
Nancy Kress Beggars in Spain
PJ Farmer
What? Nobody has mentioned David Brin yet?