Try signing up at the http://www.airfarewatchdog.com site. You can designate the airport you want to fly from and get periodic emails with good flight prices. Here's their blurb:
AirFareWatch is the only airfare alert and comparison site that includes fares on *all* airlines, including Southwest, Skybus, Allegiant, and JetBlue. If you're relying on any other source, you're not getting the full airfare picture.