A great item on eBay are these little solar-powered LED flashlights.
We got a bunch for under $1 each, and love them.
The kids no longer are draining the batteries of our other lights.
They are pretty cheap and bust often, but are full of nerd goodies so we find new uses for them.
This one died - battery OVERcharged when left in the car for 4 hot days...
We have lots of spare 'coin' batteries to fix it.
But wait! Remember all those $8 video 'spy' cameras? They both run off a small 3.6V battery... so why not combine the two!
The FIRST solar powered video camera! Smaller than a credit card!
Stay tuned on this one. We will need a separate battery to power the ucontroller to detect the intruder, turn on the camera, then turn on the video mode and pan the camera. We're about done with it, though!