Here's an awesome DIY cellphone charger from Global Cycle Solutions. As the company notes, you can charge while riding, "or spin the wheel in place to charge your phone while at home." Now that's handy.
The company also notes that the phones charge as fast as they would plugged into an outlet, but of course that depends on what kind of phone you have and how hard you pedal.
Every day, DVICE selects fresh images, videos and more from the wonderful world of technology. See them all by clicking this link.