This is a really cool Orange County Register story from a couple of weeks ago on Cheeming Boey, an artist whose work involves amazing, intricate drawings... on a canvas of foam. Styrofoam cups, that is. Pretty awesome stuff: His foam cup drawings sell for hundreds.
It apparently started as a handy, random spot to doodle, fished out of a trash can. Soon, the art-on-styrofoam obsession became his thing, and he had a collection on his hands. And now they sell for hundreds of dollars! Check out this slideshow of his awesome work.