Its well known that airlines like Southwest and Jetblue don’t usually allow travel meta-searchers to query their databases, forcing you instead to go direct to the airlines own websites to search and buy flights, rather than through a third party like Sidestep.

Southwest have a weekly ‘Hotfares’ page and an email newsletter but no RSS feeds. They do have a little downloadable application for your desktop though called ‘Ding’. It might be worth the download.