I actually use the Steam IM thing quite a bit because of people I met through forums since nobody seems to use MSN or anything else anymore, but now everyone is on Steam for games...also a number of my real life "friends" (since most of them live in other states now) came in for TF2 and L4D2 after TF2 went free and only a few people are still hanging around on AIM.
Though I cleaned out like 90% of the people who just add you after you play with them or whatever that I had clogging up the list, really should just pair it down even further. Usually talk to 15-ish people at least once a week or so though.

That OP was just so pathetic sounding lol "Are they really my friends?!? Do they even really care about me?!? What a terrible day!" Like real life friends have never stacked pickup game teams or shit like that.