CHICAGO, ILLINOIS, USA: JUNE 28, 2006:  United Airlines customers line up for service at a Chicago O?Hare gate, unhappy about the overbooking of a flight as airline passengers pass through busy terminals at Chicago's O'Hare airport, a hub for United Airlines, during the busy summer travel season, Chicago, Illinois, USA, June 28, 2006. (Photo by Jeff Hutchens / Getty Images)