Since I'm late to this thread, I find that most of my favorite posters are already introduced. All I can do is introduce two favorites of mine who currently don't post here. But they might come back---and even if they don't, the post they've contributed are well worth re-reading.
Terry used to post a lot on religion, and on the corners of philosophy surrounding it. You can get a pretty good glimpse of her temperament by reading her profile: "Argue with me, present well-researched facts and intelligent opinions, tell me what you believe and why, point out flaws in my logic, and we will learn from each other. Post falsehoods, distortions of the truth, pointless platitudes or illogical arguments and you will find that I do not suffer fools gladly." Especially the latter part. (Hehee.)
Another poster worth re-reading is
Debra Law. As her name indicates, she's a lawyer. She posted a lot about civil rights, which she's very passionate about and very competent in. I have never learned as much from any other single poster on A2K as I have learned by arguing with Debra (and usually losing).
Actually, the same is true of
joefromchicago, who is still a very active poster here---but he has already been introduced. Everything the others said about him is true. I would add that the hardcore born-again baptists have expelled him for being a religious weirdo---he believes in the Chicago Cubs.