You generate a tremendous amount of energy as you pump the pedals on a bike to get from point A to point B. Energy that can now be easily harnessed and also used to charge your small electronics with the BikeCharge dynamo.
Similar devices have existed for years and are typically only used to power a headlight on a bike. But in addition to keeping a small LED light aglow, the $100 BikeCharge has two USB ports that provide 3W of 5 volt DC power to your devices as long as you're maintaining a speed of just over 12 mph. Of course to completely charge something like a mobile phone you'll need to ride for at least two to three hours, but even short trips should help prolong your phone's battery life. And if you find a way to connect the dynamo to an electric drivetrain motor, you just might have the world's first perpetual motion machine, right?