Today only, Southwest is offering a special deal from it's Facebook page for 50% off any "Wanna Get Away" roundtrip fare booked today for select travel dates. If only one leg of the trip is on a valid date, then the discount is applied to that leg only.
Promo code is LUV2LIKE. See page for more info.
Valid travel dates: 9/5, 9/11, 9/18, 9/25, 10/2, 10/31, and 11/6 (2012)