For Earth Day, the Jones Soda Company in Seattle switched off the lights, and powered their office using 9 pedaling employees.
Sounds like it was really quite "low-tech." The stationary bikes spun an old car alternator, which recharged a battery. The battery was used for whatever they had running in the office. (If I'm wrong, please correct me... I doubt a car alternator could provide more than maybe 1000 watts. Which wouldn't be enough juice to power a toaster or a hair dryer. They must've really been on "impulse power" in the office all day. But it's some interesting symbolism.)
Here's something for you to consider.
If it takes the efforts of 9 cyclists to spin a car alternator, how much bike-power would it take to spin the alternator, and maybe an A/C compressor... and also actually propel a 4000-pound vehicle down the street? It boggles the mind to think how much energy the typical car-commuter requires, to get from Point A to Point B. (And multiply that by the millions of car-commuters out there, on any given day.)