Harmony App

While I was checking the Armando Serrano blog  I found this website, it's a kind of app for web where yo can sketch but you can't erase, it have some amazing brushes.... and it is really easy to use; the most amazing is that detects the pressure of my digital tablet..

It works taking the line you've created and some algorithms randomize some vectors from it, so it looks like a conscious cross-hatching

http://mrdoob.com/projects/harmony/