In Hamburg, Germany, college students at the International College of Communication Art and New Media have developed Citylight billboards which the public can spray using their mobile phone’s bluetooth capability. The LCD citylights accept a cursor signal from appropriate phones and the spray is immediately visible on the board. A prototype was developed for the Marc Ecko clothing brand, though it’s not clear whether the advertiser had anything to do with it. How any real world use will eliminate abuse (rude graphics, naughty words) is also unclear. But you lot out there might get a bright idea.