Here is one I just came across:
Spiral Graphics Use the link it is not a .com address
This is a cool software texture maker with many uses if you let your imagination go wild. While it is $149 USD for basic and $899 USD for Studio you can download the viewer for
free. It will render out tileable images from its preset catalog. All the presets can be tweaked. It even makes some cool planets but the light source is fixed in the free version.