Once again, I'll refer to 3DSMAx.

When a shadow is cast in blender, has a certain density to it. This density seems to be 100% opaque. Now in 3DSMax, you can set the density of the shadow so it's "opaqueness" is less. This lets more of the color of the object that the shadow is falling upon shine through. So in a way I am looking for the alpha fader for shadows in blender.

As I type this I realize, I can render out a shadow pass and then composite it back together at whatever density I desire, but in 3DSMax that is built in to the renderer. It seems like a natural thing to be there, but I guess Blender does not have that (yet!)

Thanks for the replys.