This is probably the best tut I've seen on shading and texturing.

What is that polar coordinates thing though? D:
I have to calculate the curves for the top myself. Are you saying that photoshop does that for you?

I think the coloring on a new layer is an interesting technique. I've done something similar once to give my metal heads a dull metallic color, where I filled in with a fraction of opacity over it. Is that what you meant?

Meanwhile, I'll still look for a good tut for hands and feet and easy ways to make them seamless.

Again, great tutorial!