Thanks for comments, folks!
I was trying something more painterly approach, so I was deliberately messy.
I think my usual style is a bit too clinical.
@mahvin: Yes, that was deliberately shoddy, but I think this kind of boundary search is useful, I'm learning new things.
@Willy: This kind of superhero style is admittedly like body-painting exercise. And I agree that the lighting is... creative.
@Oregonian: Griatch will be there first, I'm sure. I very much amateur.
@Griatch: Yes, Freestyle is "flavor" of Blender which can make really nice line rendering. GraphicAll has compilations, if you want to check it. It probably will be included in official Blender release somewhere near 2.6 release.
For step-by-step, how many times I need to write oops-not-that-oops-not-that-either-oops-wow?
Basically I scanned my pencils with XSane. Then I traced ("inked") characters with Karbon. I used Karbon just because I like the feel of the line. Inkscape or Gimp can do the same. Then I quickly whacked a 3D model of the background and line-rendered it with Freestyle postprocessing engine.
I combined the parts and begin coloring with Gimp. I used grungiest brushes I found. It's very nice that Gimp can use Photoshop brushes because the Internet is full of those... Then, after all that, I just slapped speech bubble and text on in Inkscape.
Summa summarum: There's huge amount of tools floating around, I recommend having fun with as many as you can. That way you can find those you like most. Gimp has such large set of features, that I at least find something nice every time I use it. (Did you know you can perspective transform paths? I must try THAT sometimes...)