If you concious of the environment and you want to get fit, the EcoMill is an eco-friendly gym treadmill which uses the energy generated from your running to charge an internal battery. The internal battery is then used to power the treadmill display and the elevation system. The EcoMill is a great alternative to conventional Treadmills that use electricity to drive the treadmill motor.
It was only a matter of time before a treadmill was designed that runs on human power. Cross trainers and exercise bikes have been doing it for years. However, the price tag is a little nasty, the EcoMill costs a hefty $8500 (£5100)! Although you could just go outside to get your exercise and save a ton of money, at least the EcoMill will encourage you to exercise indoors when the weather is too cold or too wet!
Source: Coolest Gadgets