If you do, check this site out. It seems to have quite a few good mods and campaigns. We all had a blast on the Diescraper campaign.
apparently (I'm not doing it) you can have common infected replaced by angry german kid. [video=youtube;q8SWMAQYQf0]http://www.youtube.com/watch?v=q8SWMAQYQf0[/video]
I dredge up this old thread to inform the Shieldwall that today (Christmas day) Steam is giving away L4D2 for free. All you have to do is go to the store page for the game and click the button to install it and you're good. Their servers have been a bit spotty today so it may take you a bit to actually get the store page to load. So, for any of you who don't have it yet, I encourage you to pick it up. I don't play the game a ton these days, but I always have a good time when I boot it up with a few friends.