Imagine two scales at the airline ticket counter, one for your bags and one for you. The price of a ticket depends upon the weight of both.

That may not be so far-fetched.

"You listen to the airline CEOs, and nothing is beyond their imagination," said David Castelveter, a spokesman for the Air Transport Association, a Washington-based trade group. "They have already begun to think exotically. Nothing is not under the microscope."