Got a shock to find this one staring back at me today. Some wrongly connected nodes and textures giving a freaky render.
Here's a preview of the node graph I'm using to mix up the AO, Shadow, Flat Color and Freestyle Passes, otherwise known as the 'spaghetti system'. It masks the freestyle pass using objects from the sets, edge detects to give a line round the shadows to match the Freestyle line, and adds a slight transparency to the characters when comping them over the backgrounds. The backgrounds get a slight blurred underneath and just around where the characters are to help the characters stand out a bit. I'm also mixing in ink and paper noise as freestyle's textured stroke rendering isn't supported yet in blender as far as I can tell.
I'm working with three Freestyle shaders (and a common functions module) which I coded based heavily on T.K.'s fantastic examples in the blenderartists thread.
I'll post the source when I've got them finalised.
Back to animating.