This was made in just under two hours in Photoshop. I was inspired by GSC gameworld's early build of their game S.T.A.L.K.E.R. Shadow of Chernobyl. Sadly, I had to return the beautiful Intuos tablet to school, and was thus left to scratch out this on my little graphire.
I used quite a few texture brushes for this one. I like to make my own brushes, and messing with the jitter functions in the bursh menu can create some pretty good results.