I was on Polycount last night and decided to check out one of the game threads, and oh my, I think I've found what could possible be the greatest game ever made.
It's basically a mod where the only objective is to survive (borrrrrrring, cliche!), but set in a post-apocalyptic, zombie-overrun world. The servers are running 23 hours a day and the game world is persistent. You spawn in the world and have to scramble around for weapons, ammunition, and food/water. You need this stuff to survive, and have to constantly be on the move to get more.
However, other people are doing the exact same thing. You can work together with people, or you can rob people if you're so inclined.
Watch this video to find out a bit more. It's part 2 of 2, so watch the first if you're super interested, though it is a bit more slow paced.
It has a very 'STALKER' esque vibe to it, and I love the idea of a community, survival based game. I'm gonna get it when I'm back off holiday!