Electronics projects are power-hogs. In order to run your newly-built gizmo, you need to be close enough to an outlet to plug it in, or have enough charged batteries to power it without an open socket. Of course, if you've just used up your last nine-volt, or the power has gone out, you're out of luck. Well, usually.
Instructables user nevdull has come up with the solution: A hand-cranked power supply for Arduino and other AVR microcontrollers.
Using the parts from a small dynamo-powered flashlight, a couple diodes and a little soldering, you'll end up with a mini-generator for your projects. Hook up the two leads to the Vcc and GND pins (in the right order), and you're in business.
Blair Hanley Frank loves his collection of wind-up toys.