Here's one that spit-shines the environment in two ways at once: it provides a cleaner source of energy to charge your cell phone and other electronics, and it also encourages people to shed some of that extra weight that us Americans are so well known for. Two birds.
The cell phone charger or much more poetic and foreignly-delicious "Cargador De Celular", brought to us by designer Lola Mensa, converts your kinetic energy into power for battery charging. Strap this baby to your foot prior to jogging, jazzercise or whatever other form of fitness speaks your language, and the forward motion of said foot will charge the internal battery using a kinetic mechanism similar to that which a windable watch uses to give you the time.You can then charge your device batteries from the stored power.
Now you have both a means of charging your phone and a reason for quitting the excuses and getting down to some serious step aerobics. Or at least you will if and when this type of device passes the design phase and enters production.