is there any free FilterForge-like Program?

I just started using Unity3d and I am following the tornadotwins tutorial on youtube (which is really great btw)

so I was wondering if there was any other program that does the same thing as FilterForge, or basicly I'm just looking for a Huge package of materials.

I don't really want to spend any money since I'm just starting out and doing this for my own entertainment but I still would like something good.

Thanks in advances for your answers!

edit: I forgot to say that maybe I didn't look hard enough, but I did not find any other posts with information I was looking for

MapZone (procedural texture generator) may fit your requirements, though there's a bit of a learning curve!