--> DOODLE BUG <-- is the cutest thing ever! You doodle and there's contests and stuff, though they give you just one pen tool and a certain amount of ink. It's very minimal, which is part of the challenge. Check it out! Squee. XD
This is an example of what you can do with a certain amount of ink and a minimalistic pen tool! (Not that I can do something like this. XD):
I go pee now, because I have to pee.