Comic book appearance

[paulscode]

I am thinking about making some children's educational games, and one effect I'd like to achieve is for each frame to look like a 2D drawing in a comic or colloring book.  I've been playing around with various settings and textures, and so far I get the closest to my goal if I use only ambient lighting and texture a black "outline" on the edge of each component (for example around the waist and ankles of a pair of pants).  The main problem is somehow drawing an outline around the visible edges of each object.  I'm thinking I could duplicate each object and texture one completely black and scale it up a tad, then use a pseudo-billboarding effect to always have it behind to other object.  I thought I'd see if anyone here has some additional ideas I could try to improve the effect I'm after.

[fireside]

A lot of cartoon shading is done with shaders.  Since jpct has those now, it would probably be the best way to go.

[EgonOlsen]

There's also some source code in on the download page that Klaudiusz once wrote that tries to create a cartoon render effect without using shaders. I'm not sure how good it is though.