GMLFlip is a tool developed with Processing (http://processing.org) for the Graffiti Research Lab France (http://graffitiresearchlab.fr)
It allows you to draw graffiti, freely or guided by a background picture dragged & dropped in the drawing area. You can then save it as images that you can use to make flip books or just save your drawing as a GML file.
GMLFlip uses the sDrop and GML4U libraries. http://www.sojamo.de/libraries/drop/ http://git.com/01010101/GML4U
Watch a video presentation on Vimeo http://vimeo.com/grlfr/gmlflip