The Washington Post had a very helpful rundown Sunday of several online fare watching services, which allow you to track the lowest fare on a specified route and then pounce when it drops.
The conclusion: Farecast’s Farecast Alerts ranks highest — but none of the services are a substitute for poking around the Net for low fares until your eyes cross. That’s my usual method.
Anyway, I think this fits nicely with my Sunday blog entry about when to buy airfare. That’s why I brought it up.