You can download a program that notifies you of special Southwest Airlines fares. They are usually really good fares, some for dates in the future, to ensure a set amount of sales each month, as well as short term offerings to fill up planes.
I am hoping for a January 2008 ding so our grand gathering can lose our 9 hour drive and fly instead. Gas will cost us about $300 round trip each car not to mention wear and tear on the two vehicles. If we get the ding that was out yesterday for travel through Nov 14, it would have cost us $400 plus tax/fees. A $100 difference...definately worth it.