The Glocal website has got the MAKE site pinned on this one: an open source, Arduino-powered, Altoids tin-encased digital photo hack. From the site:

This Arduino-based hack lets you take pictures by triggering your camera’s shutter on a time delay (every ten seconds, every 20, every ten minutes…), or by plain old sound: you make a noise and the camera takes a picture. We’ve been perfecting it and it is very sensitive- anything from a whisper to a loud sound will make it trigger the camera.

Schematic and Arduino code included.