This guy set the world record for distance traveled under a human-powered land vehicle in 24 hours (650 miles).
But what's impressive about it is that with their testing, they found that you can go 28 mph in this vehicle with just 100 watts! WOW.
(And just to give a comparison. Using http://www.kreuzotter.de/english/espeed.htm to guage watts required to go a certain speed, if you had 0 mph wind, 0% gradiant, were 0 ft above sea level, weighed 160 lbs, had a 19 lb bike and rode at 100 watts, you'd go about 14 mph)
It uses clip pedals and a regular bike gear system.