Interactive art can and often does walk a paper thin line of being awesome and being completely naf. Half-arsed instillations you can poke, twist or slap just don't really cut it and are best left for Science Works or the Bermuda Triangle. However, when they're done right like French artist Antonin Fourneau's Water Light Graffiti, they can be mind-blowing.
Using a huge matrix of LEDs embedded in a moisture sensitive panel that illuminates when hit with water, Fourneau has created one of the coolest interactive works of art we've laid eyes on. Basically, anything that shoots water eg. a Super Soaker, those garden spray things, a hose, even a mouth full of water can be used to create a completely unique and government friendly work of 'graffiti' art.
Check out the vid below (in French) showing how the Water Light Graffiti was created.