Comment Get a Canon with CHDK (Score 1) 106
A large portion of the canon cameras support CHDK (canon hack devkit). One of the nice features included in this is motion detection. This requires no external components to get it working, as it uses the CCD for triggering. There are numerous scripts that use CHDK to implement delays, time laps photo sequences or other funky actions. Most of the supported cameras are fast enough to capture lightning.