Actually, now that you mention it, I just recently rediscovered Steam (I'd been a registered user since way back when when I purchased Half Life 2, but haven't used it since that year) because someone had mentioned a sale they were having on...I dunno, Company of Heroes package or somesuch.
In any case, I now use it exclusively to launch/keep track of all my games/gamer friends. Even with games that I previously (pre-Steam) owned, I just point the client to the executable, and it lets all my friends (via Steam) know what I'm playing.
Tiny memory footprint; usually inexpensive games and (after the interminable purchase/d o w n l o a d time) has a wonderful backup system, so's you always have a copy handy and don't have to worry about (gasp!) using the terrifically slow download setup again. But, if all else fails, one has THAT as a backup option, as well.
I'm diggin' it.