Chris Lund, over at Prawfs, points out this sale at Spirit Airlines: you get $50 off on a round-trip ticket. But this is some fine print!
* * Coupon usage/booking must be made on spirit.com by 11:59 PM ET on April 25, 2011. This offer is valid only on new, non-refundable roundtrip bookings made for travel from July 3, 2011 – July 4, 2011.
All this from the airline that charges for soft drinks, exit rows, seat assignments, carry-ons and surf boards.