I've used some Citadel texture paint on the bottom. This stuff is basically thick paint with grit in it. I like it well enough, but not better than some of the other texture mediums I have - and those are cheaper, and you can make them any color by mixing in whatever paint you like.
I have to wait for the texture to dry, but then will hit it with a wash and some drybrushing to highlight. Then these guys, in all their leathery glory, will be done. And I'll only have 9 more to finish!