This is the Zombie make-up I did for my BF for the Helloween party we recently attended. I used clear liquid Latex over toilet paper. It is a very nice cheap way to go about the rotten skin look. [link]
this linl is to a very good youtube video that's shows you how to do the cheap FX.
It normaly takes about a hour and a half to aply the latex and make-up. But this depends on how many layers you do.