This one is more about cool than about saving money. Sure, it uses a small crank to power itself rather than using batteries. That's the extent of the savings. But the cool part is that it's a full-featured emergency flashlight, perfect for your glove compartments. (note the plural...I've got one for each car)
It fits nicely in the car, but it's no keychain flashlight. It's much more substantial than that. The light is bright and has multiple modes including a flashing red/white mode to go along with the standard flashlight mode. Plus it floats and is fully waterproof, not just water resistant. It can be submerged 33 feet. (At least that's what the package says. I only let my 2 year old try it in his bath and it worked great!)
Only around $13 with free shipping...
Life Gear LGWL05PRO Waterlight 0.5-Watt PRO, Yellow