Well it's not an standalone, it's even a little bit expensive in fact, but I never seen something as clean as FinalToon (for max) when you're looking for sharp and cute outline.

http://www.finalrender.com/products/images/finaltoon/gallery/androbot.jpg

http://www.finalrender.com/products/images/finaltoon/gallery/Motor-shady-outline3.jpg

http://www.finalrender.com/products/products.php?UD=10-7888-35-788&PID=37

... now is someone has a standalone render engine close to this I'm really interrested to :)