Here's an interesting way to power a camera: attach it to a fluorescent light. This small wireless security camera by NEC takes advantage of electromagnetic induction to keep itself running, thanks to a ring-shaped adapter made by Sharp that draws from the magnetic fields created by the light's AC power source. The ring reportedly is able to generate 120 milliwatts of energy, and that's enough to operate the camera and its internal wireless chip.
The camera itself transmits photos every 10 seconds at the-usually-grainy VGA resolution. At the moment it's just a prototype.