Electricity Free Lighting
Check out this neat idea:
Water and bleach in a bottle fitted to a roof, refracts and reflects light to the interior of a building. half of the bottle is outside and half inside, refracting light equivalent of a 60 Watt bulb without the need of a power source. A drop of bleach in the water keeps it clear and germ free.
Go here to read more: http://dornob.com/solar-bottle-lamps-water-bleach-10000-liters-of-light/