Utilising Human Energy  

I found Chevron's use of the phrase "human energy" in their peak oil forum rather sinister, but Boing Boing has a post up about a rather cool use of excess human energy - a water pump driven by playground equipment in Africa - the Playpump.

Playpumps are specifically designed and patented roundabouts that drive conventional borehole pumps, while entertaining children. The revolutionary pump design converts rotational movement to reciprocating linear movement by a driving mechanism consisting of only two working parts.

This makes the pump highly effective, easy to operate and very economical by keeping costs and maintenance to an absolute minimum. The pump is capable of producing 1400 litres per hour at 16 rpm from a depth of 40 metres and is effective up to a depth of 100 metres. A typical hand pump installation cannot compete with this delivery rate, even with substantial effort.