I stumbled across the simpsonizeme.com website [http://simpsonizeme.com/] which takes a photo and converts it to a Simpsons style caricature. You can then manually change the features if the suggestion is not quite right. A few changes later and I ended up with this -- close, but maybe a bit too old/yellow. :)

There is also a different manual simpson avatar creator at [http://www.simpsonsmovie.com/] which is also quite fun to play with.

It's fun to think of the huge parameter space governed by these systems, and maybe an aesthetic/genetic selection mechanism would be better suited to searching through the space or automating the creation of new characters.