I love people who think outside of the box and if you can tie that together with art, activism and making money...then you really are on a whole different level. I love what Moose does as a graffiti artist and I hope try it out in DC sometime. It's really brilliant.
"Moose is the pseudonym of Paul Curtis, a British graffiti artist. Instead of the typical methods of graffiti, Moose works by cleaning dirt and grime off surfaces to create his art. He is a commercial artist (Symbollix), and has been paid to create works for products such as Xbox and Smirnoff."
Moose -- Wikipedia
"A British street artist known as Moose creates graffiti by cleaning dirt from sidewalks and tunnels -- sometimes for money when the images are used as advertising. But some authorities call it vandalism."
Artist Draws 'Clean' Graffiti from Dirty Walls--NPR
The Reverse Graffiti Project
Check out the Reverse Graffiti Project.