The Nero Multi Trigger is a nifty camera triggering device that can make your DSLR and external flash unit respond automatically to sight, sound, and motion. It has built in optical, audio, and laser sensors, allowing you to shoot everything from lightning flashes to balloon pops. There’s also an intervalometer for time-lapse photography. The device mounts to your DSLR’s hotshoe and is powered by a pair of AAA batteries. They cost $200 each and are available for both Nikon and Canon DSLRs from the NERO website.