LEDs are not only incredibly energy-efficient, but they're also small enough to be squeezed into the tiniest of gadgets. Or in the case of the Lite Lite, a simple piece of paper that folds into a working flashlight.
There is some assembly required, of course, but it's as simple as folding a piece of paper into a long square tube and slipping an elastic band around one end to hold it together. That's it. The $13 flashlight is powered by a single cell-sized battery which should actually keep it shining for a while, and turns on automatically whenever you grasp it.