The Camera Axe is an open source system for doing high speed camera triggering. You know all those pictures people get of balloons popping or drops of water in mid splash? This is how they do it. The system has light sensors and sound sensors to help get the timing just right. It can trigger your camera and the flash to capture images at just the right moment. There are a lot of picture examples on the site as well as a full schematic and parts list. Not too bad for roughly $100.