Recharge your cellphones by going for a walk

I have seen bikes used for charging cellphones while attending a music festival in the desert at Coachella, and I have seen knifes being sharpened in India with energy generated from the same pedaling action, but today I have heard about technology being developed that would recharge mobile phones simply by the motion of walking. For a man who is notorious for running out of batteries on my cell phone in the worst times, such as downtown Chicago an hour before having to meet my ride back home to Kalamazoo, this is the technology I have been dreaming about.