The airlines' most brilliant, if little noted, post-deregulation marketing ploy: introducing a new class of cheap fares, but only on nonrefundable tickets, which carry stiff penalties for flyers who need to make changes. When American introduced the first "supersaver" fare in 1985, it really was nonrefundable: if you didn't use the ticket, you were out the whole fare. Starting in the early '90s, the airlines became more forgiving: for a fee of $25, you could rebook that nonrefundable ticket for a later time. Since then, however, the change fees have been ratcheted up steadily, so that now, in most cases, you've got to spend $150 to switch the return flight on your round-trip from Sunday to Monday — plus any difference in the basic fare for the new flight, which can be substantial.