You guys may have a use for this: http://www.mapzoneeditor.com
It's a texture creation tool that works in a procedural way and (once you understand how it works) lets you create some amazing looking textures, especially organic/natural type surfaces. It can also be used for creating skins, however that is very complicated indeed.
You guys may want to have a quick check through the license on teh download page, but it allows the textures created with it to be used for comercial purposes, so I believe anything that has been created with it could be GPL'd.
Here's a couple of shots of textures I've made while playing around with it:
No artistic talent required, just a technical mind to figure out how it all works.