I've been working on my blog's head picture for hours without luck. And finally I've found http://www.sketchswap.com/
Have you tied it? It's really simple, only white canvas and a brown pen. It's not possible to erase or change the color.
These flash program save all your traces and share it as a flash movie with someone who submit another drawing. The main objective is to submit your drawing so you can watch other's.
Give it a try, its fun!
Yes, I know is not good at all but is the one I've been looking for!