lots of contenders for the killer app that'll take the iPad to the next level, and we think light extrusion is currently near the top of the heap. Dentsu London has paired accelerometer-based software with long exposure/stop-motion photographs to take 3D renderings into real space, with a result that reminds us of the Graffiti Research Lab. Sure, you could do this on an iPod touch, but it's that real-world iPad bigness that makes it awesome -- one of those moments that makes you sit back and say dang, future, you're here! We can't wait for this to make its way into the App Store -- and our nieces' Facebook albums -- ASAP. Crazy light painting video after the jump.