I'm not really an RTS guy, so no SC2 for me.
And apparently no L4D2 either. Steam has taken up the habit of deleting half the game files from my hard drive whenever it sees an update for the game. I played it last week just fine, but then they updated and now it wants me to download 4GB of stuff I already had. No idea why its doing it but unless I get to a book store and update with my laptop then its a no-go. And even then it'll only hold until they update again...which with their mutation gametype things seems to be weekly. This is going to get really annoying, really fast.
But I'm down for some Alien Swarm (until they update it), Guild Wars, Demigod, or maybe even some Doom 2/Skulltag action.