Who's on first?

First off, let me say that Lin and boriel, though much loved, are not in here as they seem to have been well-covered already. Instead I name them here, in a place of honor. :-) There are still so many who I had to leave out - what a varied and wonderful group of people we have here... I expect many will be easy to figure, though I tried to be vague. ;-)

( The 15-person guessing meme rides again... )