Hat's off to zerosign.net for linking to the I/O Brush demonstration. This thing allows you to "dip" your brush onto any surface and then "paint" with that color, pattern or movement. It's hard to explain so check out the video.
(By the way, has anyone else seen the movie, "The Peanut Butter Solution?" The villain uses magic hair to manufacture brushes that miraculously paint masterpieces of anything you can imagine, with little or no artistic skill. Ghosts fit in there somehwere too. It's a strange movie, but this "I/O Brush" reminded me of it immediately. )