CartoGraffiti

CartoGraffiti is a collaborative painting web application, using the Earth surface as it's canvas.
Pick up a location from Google Maps and make your art, with brush tools, stencils and stickers.
Once drawn, It will stay there, composing a virtual art gallery that anyone can see and extend.
Aimed for iPad, but public beta will start on August 8th 2011 at http://www.cartograffiti.net/