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