"Finally added texture and other bullshit in GIMP." That... For some reason, I busted out laughing as soon as I read that part. But in all seriousness, this is quite handy, a very nice tutorial. I've always been curious about how it was you got the output that you did with your art. Very interesting. Thanks!
(Someone was awake pretty long x) ) In fact, it really looks interesting. I mean: It'd never pop into my head to try it out (probably because I'm a newb). I'd probably try some grayscale stuff, or not even that, but that kind of opened my eyes. Did you use a very low opacity or a special blending mode?