I've been using Painter to make some textures and have found this program very good for this. But also, in looking around for similar styles or what to shoot for, I found a site with an absolutely amazing load of free textures for use in 3D projects - Lemog 3D textures

Also Textures - Rock they have alot, and you can submit your own if you have them.

I apologize if this is a multiple posting of either of these two texture sources.