I like sidestep as well. It's SUPPOSED to check SW, which most other sites don't do, but I've not been finding it has been doing SW lately.
www.airfarewatchdog.com is pretty good about sending out alerts on the best fares from your city. Sometimes they aren't fast enough and you miss the best deals, but they're useful if you're just looking for someplace to go cheap.
C'mon SW, what's today's deal? No Ding! offer yet.