Travelocity has a "fare watcher" feature -- you have to register (no cost) and then designate the routes you want it to watch. You can specify how long to watch and when to notify you (ie: price goes up or down $25). They'll send you an email notifiying you of a price change for your route.
We've used this quite a bit, but we don't rely on the email part. Once you've registered your route, the home page will be customized with your fare watcher routes. It's easier just to go to the site once a day and check it out. Good luck
