To encourage customers to spend their frequent flier miles, Northwest Airlines started a travel auction Web site, http://www.auctions.nwa.com/, that takes bids in WorldPerks miles.
The site will auction vacations, trips, concert and sports tickets and things like a Zamboni ride at Joe Louis Arena in Detroit.
U.S. travelers hold trillions of unused frequent flier miles; estimates range from 10 to 14 trillion miles sitting around doing nothing.