Holy Shit Zombies!

This has got to be the coolest mod I have seen in a while, and they're still improvements to be made. The headtracking tech the guy added in there probably makes it a lot more immersive than it would otherwise. Naturally it probably makes it a lot scarier too, awesome!

Unfortunately I can't play ARMA 2 so watching youtube is the closest thing I can get. If you can play the game with a decent frame rate you might want to check this out.