Airtran has cut airfares on many of their routes for bookings made by Jan. 17 and for travel through early March on Tuesdays through Thursdays.
The lesson? Search around on websites before you jump on a deal that an airline advertises as a "sale."
[UPDATE 8a.m. ET 1/7/2008: Midwest Airlines announced a fare sale yesterday for travel through June 11, 2008. Examples include Minneapolis, Minn., to Toronto, Canada, for $204 roundtrip (a 66 percent drop in price, according to AirfareWatchdog), Hartford, Conn., to Flint, Mich., for $210, and Charlotte, N.C. to Omaha, Neb., for $189. Most fares require either a Friday or Saturday night stay. Must be booked by Jan. 15, 2008 at MidwestAirlines.com or the the top travel websites.]
[UPDATE 1p.m. ET, 1/3/2008: United Airlines is offering deep discounts on both domestic and international airfare for the new year, for booking by January 10, 2008. Sample fare: San Francisco to Shanghai for $518 round-trip. Click here for details and restrictions.]
MORE ON FARE SALESAirfareWatchdog.