Several major airlines guarantee that the fares they sell on their websites are the cheapest available. More specifically, American, Continental, Delta, United, Northwest, and US Airways make promises that go something like this: "If you purchase a ticket on our website and the price goes down before midnight for the same flight itinerary, you can make a claim and receive a refund of the difference in price plus an additional bonus."

Well, the folks at FareCompare.com recently tested these guarantees. They bought tickets, waited for fares to drop, and then asked for refunds. It turns out that the airlines make you run in circles to actually claim a refund. And given that the amount of money in dispute is often small, you might as well never file a claim. Hats off to FareCompare for its legwork. For the details, click here. And to read our advice on how to make the most of FareCompare's services, click here.