List of favorites:
Swan Song
Gone South
Stinger
Boy's Life
Baal
Wolf's Hour
Actually, I guess I should just list all his books, with the exception of Speaks The Nightbird. That is the only one that I haven't read yet, but I will soon if I get my way.
If you've never heard of him, or just haven't read his work. Go ahead and check out his site. But he writes a mixture of horror, sci-fi, and suspense. Each one with amazing descriptions that really put you into the scene and the lives of the characters.