There are at least 2 other threads about this; one of them is "Post something positive about the person above you" in the Off the Wall forum, but I'm too lazy to find them...
Greenblue, whenever you're around you always PM me, like every day, even if you don't have anything to say you still say "Hi, how are you?"
CockneyRebel, you are a stable person amongst a bunch of unstable people-- I always KNOW I can count on one of your avatars having either Sid, a Routemaster or both in it, so I know I can click on your name and look at your profile to cheer myself up.
MADDuck, you deal with all my kvetching and still you ahve wonderful stuff to say about me.
Gwenevyn, you are so nice and patient and always know just what to say!
Irulan, you seduce me (in a non-sexual way, since I'm straight) with your name, your background and everything... msot of all your INTEREST IN AUSCHWITZ!1 The eclectic personality reminds me kind of myself; I like your avatars and how they don't match your name or obsessions, really.
Berserker, you remind me of me when I badly wanted to do something and was understimmed and daydreaming of being a part of a let's-kick-the-NT-ass group...
Kilroy, you're always helping people out and telling them they can PM you; I wish I was without my issues so I could do it too.
And many more!