Check out these supercapacitors – 220 farads!
Holy crap. Instructables user mrigsby posted instructions on how to build a battery-free LED flashlight that charges in about three minutes and lasts for 24 hours. Apparently it’s about 2-3 hours of bright light, and then it drops to “night light” levels. Whatever, I guess – three minutes to charge!
Check out mrigsby‘s instructable. Very cool! This project comes from a book called Haywired: Pointless (Yet Awesome) Projects for the Electronically Inclined by mrigsby himself. This book is totally on my Amazon wishlist.