In addition to reducing pollution by taking cars off the road, bicycles can be used to bring clean water to people around the world. Check out this video about the winning entry in the Innovate or Die contest put on by Google and Specialized. The contest challenge was to build a pedal powered machine that has environmental impact. Team Aquaduct created a pedal powered vehicle that transports, filters, and stores water for the developing world. The YouTube description explains how the Aquaduct works:

A peristaltic pump attached to the pedal crank draws water from a large tank, through a filter, to a smaller clean tank. The clean tank is removable and closed for contamination-free home storage and use. A clutch engages and disengages the drive belt from the pedal crank, enabling the rider to filter the water while traveling or while stationary.