Very cool service provided by a company in Dublin, Ireland called Eco Cabs. They run a small cab operation that uses pedal powered cab rides in an eco friendly tricycle type mobile wagon.
The rides are free to pedestrians, and the cost is offset by advertising and sponsorship on the wagons. Big name advertisers such as 7 Up plaster the wagon with ads, and this enables the rides to be offered at no charge.
The eco cabs do carry a battery as back up, but they are mostly pedal powered by a human. These are available currently in Dublin, Ireland with other sies planned. Very cool.