My favorite gadget is my Eton FR150 radio. It is smaller than most of their radios, but has a real flashlight to it and its form makes it useable as a flashlight. It also charges from the USB port on my computer (with proper cable) or from sitting in a sunny window. So it is always charged when needed.
A close second is my Doug Ritter PSP, which is actually a small bag of gadgets. But I'm a wilderness survival junkie from way back, so I'm biased.