Oh, I know. I got L4D, and it's a good game.
Suffers from the same issue as TF2, though, even when playing with friends. I just think "this is a good game. It should be fun. Why am I not having fun?"
That said, I already own it - my problem is more that I'm not going to spend $20 or more on a pack just to hand stuff out to people when I have already done so twice. Semi-broke, after all.