Light powered by your "dead" batteries
This is incredible and I wish cities would make something like this standard. We have these horrible lights on our lawn that use sensors to turn on and off. Should conserve energy, but in the winter when the snow is several feet high on the lawn, the light is buried and always on, which is wasting energy. Now this, this makes a ton of sense: A light that is powered by your dead batteries (which still have some juice, but not enough to power anything else in your house).
Apparently LEDs need about 2v of power, and most trashed batteries contain 0.8 to 1.3v. The receptacle on the bottom of this light has slots for all sort of batteries, and feeds off their juice until they are truly dead. Once they are really gone, then they should be recycled but this could extend their useful life. And if these were street lights, it could encourage the neighbourhood to put their batteries in the lights instead of in the trash.
Find out more at Yanko Design.