TV characters are just hard in a style that's neither realistic nor a complete cartoon like chibis (or even things like my ratcreature icon versions, I mean, I'd like to think that thanks to costuming, props and hair you can easily guess as which character my avatar is dressed up as, even though it is a non-human big-nosed monster with weird ears, large feet and a tail).

But yeah, I've read about the caricature programs on Wikipedia:
http://en.wikipedia.org/wiki/Caricature#Computerized_caricature_and_formal_definition_of_caricature