Hmmm.

Definitely Black Company. The granddaddy of all gritty military fantasy.
Alastair Reynolds - his stuff is a bit more hard scifi than I usually read, but he can also tell a story, something that most hard scifi authors can't seem to master.
Tilt mentioned the Hyperion series - definitely up there in my top five favorite scifi reads. Also well worth reading is Simmons' two volume series comprised of 'Ilium' and 'Olympos'.
On the horror front, everyone should read 'The Passage' by Justin Cronin. Think 'I Am Legend' crossed with 'The Stand'. It is AWESOME.