This is a neat little demonstration of IPO drivers used to control textures. The demonstration uses the Mancandy model and rig. Video after the cut or you can find the video on vimeo.
Quote from author:
This video test shows Blender's bone-driven texture IPO in action on the Mancandy model and rig. I've added a bone that is constrained to scale with the finger controller bone, which drives a bump and color texture channel. The bump map is just at the knuckles and finger joints, the color map is just at the knuckles.