There are many categories for this. Certainly Whispers and the others mentioned. Some others (and I'm not sure they were on here or just ASPD)
Kosher Kowboy
Scratch Golfer never met him, heard he was a jerk, but always enjoyed his posts.
SofaKingFun
Monica Fox for, if nothing else, her "Don't take a dump at my incall" post, funniest fuckin' thing I've read on these boards in my 16 years. Although I know that one was on ASPD