Lots of gadgets call themselves wireless but really aren't. Take surveillance cameras: Most wireless models still need to be plugged into power, and those cute tiny cams have batteries that have to be recharged via an AC-adapter cable now and then. Wires, wires, wires! But if your camera is meant to be used outdoors, there's at least one truly wireless solution: this solar-powered motion-sensing camera. Ra himself powers this trusty watchdog, with a single charge keeping the camera running all night, assuming you haven't put it in a shady spot or have assigned it to keep watch on a building in Alaska in the winter. When the camera detects motion, it sends a signal to the receiver (which you've presumably hooked up to a monitor inside), telling it to chirp and let you know something's afoot. If it was just a sparrow, the 2.4-GHz camera will stop transmitting a preset number of seconds after the moving object leaves its field of view. You can cut the cables on surveillance forever for just $160.
— Peter Pachal

Smarthome, via Übergizmo