Gummistiefel mit stromerzeugenden Sohlen zum Handy-Aufladen Interessant, wenn auch noch verbesserungsfähig:

The Orange Power Wellies have a “power generating sole” that converts heat generated from your feet into an electrical current that charges your mobile phone, which you can plug in at the top of your boot. Twelve hours of walking will give your phone an extra hour of battery life.