Well, depending on your needs, and expected end results, there are a few free programs that I use in concert that do a pretty good job. At least for my needs with texture/seamless tile creation for use in the Poserverse.
They are by far not Genetica, nor FilterForge, but you can achieve similar results (to an extent) if you are diligent, and patient. The key is to experiment, play, practice, experiment, play, practice, experiment, play, practice, and then, rinse-n-repeat.
Here are some for you to check out to get you started:
*NeoTextureEdit - Genetica/FilterForge style node based procedural texture editor. Has ability to create Normal Maps (I have created normal, specular, bump, ambient occlusion, and displacement maps with this alongside the diffuse map), and also has an included OpenGL 3D viewer to see the fruits of your labor instantly:
*MapZone (By Allegorithmic) - Another free procedural texture editor, but it seems Allegorithmic has completely pulled the plug on this, and only offer their newer paid-for professional suite. Look around, you might be able to still find a download-able copy somewhere. It is definitely worth it to at least try and acquire a copy. The last version was 2.6:
(Sorry, no link available)
***Here are some other programs that might interest you, and when used with the apps above can produce some decent results:
*ShaderMap CL - Normal/Displacement/Specular/AO maps creator from diffuse map free command line version (you write the execution code, and execute via BAT files). It is pretty easy with great documentation on how to create the executable files:
*sTile - Great tiler/editor to help with your creations. Many great uses:
http://www.harmware.net/stile.htm (don’t be alarmed by his production/studio name. No “harmware” about his creations. I think he was “young-n-dumb” when he came up with his coding studio name. It has been around for many years, and I have never seen anyone reporting any problems)
*Kali - (unofficial) tile creator. Lots of possibilities for tile creation. You can create base tiles to build upon elsewhere, or you can play until you have something to use as a final. You can also create seamless tiles with careful set-up (application window), or utilizing alternative solutions:
*Illusionae - Tile creator/editor. Lots of great tiles can be created to use with the other programs, or as finals by themselves:
*Semicuro - texture creator. I find this one requires some patience, and a lot of experimenting, but can be useful:
There you go. I hope this helps.