Water power production
I found this idea really neat.
You know how if you put a hole at the bottom of a bucket, the water will naturally create a whirlpool to drain out of the hole at the bottom of the bucket?
Somebody came up with an idea to use the same concept for generating electricity. Fascinating!
http://blog.hasslberger.com/2007/06/water_vortex_drives_power_plan.html