I had a conversation with a computer gamer who also claims to be an environmentalist. It was interesting to see a person with a Toyota Prius on order and a dual processor PC that consumes something close to a kw with its big crt monitor, graphics card and over-clocked processors.
So here is my simple proposal ... environmental computer gaming.
Any PC can be used, but all power must come from one person (two person teams) generating electricity through power they mechanically provide. No batteries are allowed anywhere in the system. To smooth the load a 1 kg flywheel is allowed. Any game must run at least one hour to be considered legitimate.
There would be two divisions ... a specialist's division where an engine would not have to game and a gamer's division where the engine and gamer would trade off and their game scores are averaged.
Throw in some serious prize money and you might see some interesting innovation. It would probably make a great project at engineering universities around the country.
An added benefit would be the development of efficient human power generators for powering third world electrics as well as an exercise/tv for lazy teens (don't laugh - a friend of mine built one a decade ago so their kids could watch the Olympics ... everyone who hears the story wants to buy one).