Here is a neat idea for folks who ride their bicycle all the time. The Bicycle Turbine Light does not need you to worry about its batteries. It is powered by you. As the wind passes through it, its two way fan is spun to create the power needed to light up LEDs. When you stop riding, the light stops. There is no battery to deal with.
Bicycle Turbine Light is lightweight and self-powered. Just ride your bike, and you will have your light working. The idea certainly has potential. You can follow it on Quirky.