Cartoonize effect

Hello,

I want create cartoonize effect (image will look like it was drawn for the catroon) using OpenGL?
Or am I looking in wrong direction?

Example of this effect can be seen here:
http://www.dodownload.com/image/photo+to+cartoon+online.png
and here:
http://www.befunky.com

Thank you in advance.

Keywords : toon OR cel OR cartoon shader glsl
Read this and following pages :
http://www.lighthouse3d.com/opengl/glsl/index.php?toon

Drawing black edges or stroke outlines can be done too.