Three enterprising (and sober) college students in Colorado have found a way to lighten the pockets of their determined-to-go-partying colleagues and neighbors.

Three years ago they founded NightRiders, a designated-driver service that safely deposits the inebriated and their cars back home after a night out. They use collapsible scooters that fit in a trunk or back seat to go from one pickup to another.

Last New Year's Eve, 350 people caught a ride from the 'Riders, paying a flat rate of $15 plus $2 a mile for the trip. The company's most effective marketing tool is a poster that compares their fees to the cost of a single DUI conviction, which in Colorado can run into the thousands of dollars.

"The sad fact of it is," says cofounder Brad Dickerhofe, "people are more concerned about being busted than about putting lives at risk."

NightRiders is expanding their company, and similar businesses are popping up across the country (Time magazine, Jan. 17).