Attached Link: http://www.redfieldplugins.com/

I'd like to mention the Redfield Plugins site. There are several free PS plugins which also have use in making textures and heightfield maps for 3D apps. The updated (and free) "Craquelure 3D" is awesome for making useful textures, and the Lattice Composer and Water ripples are fun, free, and useful too.