Balls (Baoding) will recharge batteries!

[SumitB]

Baoding ball, or better known as Chinese exercise ball is able to exercise your finger and hand and more importantly, it is believed to have similar effect of acupuncture which stimulates your acupuncture points for better health and life. And good thing now, while you are playing with the baoding ball when watching the TV, reading book or doing nothing, you are actually able to charge up either AA or AAA size batteries without really realizing it. There are even LED indicators on the ball surface to inform you if the battery charging capacity is already full or still needs some more exercise.

Source

I hope its not expensive!