Airlines lower fares on different routes everyday without advertising the price cuts. A fare could be $400 today and $98 tomorrow. And then $500 the next day. To book the absolutely lowest possible fare, you have to look at fares on the routes you want to fly every single day for a few weeks, and then adjust your schedule to whenever the fare is lowest. That's what the folks at Airfarewatchdog.com try to do with their email newsletter.
In a new feature, you can choose your city-to-city routes or departure cities and how often you'd like to be alerted to fare changes.
The service is free. You have to hand over your email address, but the site promises not to sell or share email addresses, and hasn't done so in many years of operation. Another perk: It's the only airfares web site that tracks all airlines, including Southwest, as well as promo code airfares.
The catch, of course, is that you have to have a trigger finger that's ready to book your ticket as soon as you see a good deal. Many of the deals that Airfarewatchdog finds are here-now-gone-an-hour-from-now. So be sure to act fast.