Here's some cracked earth. Unofrtunately I had to merge layers and do resynthesizing on itself for better tiling.
Unfortunatley GIMP always saves a 32-bit TGAs, so I'd have to always nuke an alpha channel to get it down to 24-bit. Releases will have these in JPEG form, mass converted by script.
The cracks are made from generated voronoi patterns, then curved, then ran through a texture transfer...
and even at 512x512 I still add a detail texture layer