All kinds of SF. Comedy, serious, novels, films, TV, cartoons, web comics.
Isaac Asimov, Douglas Adams, Arthur C. Clarke, Poul Anderson, Robert Heinlein, Frank Herbert, Terry Nation, and I just realised that my favourite writers are all dead. Hm.
Oh wait. Grant Naylor.
My avatar is the Red Dwarf (the original one that is, not the more streamlined one from the later editions of the show). I had a picture of Dave Lister at first, but people got confused.