This isn’t a brand new hack, but it’s a great solution for most digital cameras that like to go to sleep on you.
[T. Black] put together a nice simple pic circuit to control a cheap aiptek digital camera. It uses a 12C508, a cap and a resistor. The PIC not only activates the shutter, but can wake up the camera from sleep mode. You don’t even have to provide a dedicated control channel – it can piggy-back on the throttle control signal. The hardest part of the project is tapping the signals on the SMD pc board inside the camera. There have been quite a few R/C camera controllers built, but this is certainly one of the most elegant. You can grab the code and schematic from the bottom of the project page.