A friend sent me this link:

Click on the thumbnails and run the application to view the artist create a digital “painting” only using a pencil/brush-type tool and a smudge-type-tool. It’s amazing.

The bird ones take a while a complete but are worth watching through; the other two are on super-speed.

(Click on the screen to pause it, and you’ll see a play or stop button show up as well.)