Wow, I'm surprised at how similar my taste in books is to most of you. But then I remember what forum I'm trolling...
I got introduced to Terry Pratchett's work in Germany, where I read 9 or so of his books. I started on his early stuff like Equal Rites and ended with his later novel, Nightwatch. I really liked his early stuff, because it's just so silly, but his later Vimes stuff is just as interesting to read, though it's much more mature.
Anyway, I also love Hunter S. and Stephen King. Just finished Moby Dick, which I think is a fantastic read. Douglas Adams, of course, but that goes without saying. Orwell, Vonnegut, Kafka, Huxley, Bradbury, Burgess, Neitzsche, HG Wells... Does anyone else know Daniel Quinn's work?
I can't remember the authors, but I also really liked Snow Crash (Neil someone wrote it, I think), Riddley Walker, and Grendel (the story of Beowulf told in the first person by Grendel).
I own the Amber book which contains all the stories, but I haven't cracked it open yet, because its size is a little intimidating.
And I write occasionally, but I always end up abandoning all the projects I start, due to my impairingly extreme perfectionism.