I love all of these things that valve does with L4D. When it first came out, I was able to convince 2 other people to buy it with me, and we played the hell out of it. And every time valve throws some awesome sale, or trial, or free content, I'm able to convince more and more people to buy it. Seriously, if they ever release a pack that contains Left 4 Dead, Team Fortress 2, and Portal, they could call it the 'valve rules you box', and it would be the best fps pack evar.