Finding the cheapest airfare is a game -- and often, a maddening one at that. Flight prices fluctuate all the time, and the only way to monitor all the ups and downs is with frequent searches. This can obviously lead to shopping fatigue: Who has the time to punch in dates and destinations into a handful of booking engines several times a day?

A few websites have begun doing the searching for you. The best option of all may be a website that came out of beta-testing this morning, Yapta.com, whose entire mission is to handle all of your searches for you. Membership is free. Once you join, plug in your dates and routes, as well as a price threshold. The site will do several price searches per day, and as soon as the flight drops to that specified price, you'll receive an e-mail alert. Members can also download Yapta's software and get messages instantaneously on their desktops.

Yapta not only tracks flights you might want to buy, it tracks flights you've already bought. Why? Because occasionally fares drop so low that airline ticket holders are entitled to a cash refund (minus a change fee of $100 or so). It's rare but does happen. Yapta also tells members when they're entitled to a flight voucher from an airline; it's a little-known rule with some airlines -- Alaska, JetBlue, Southwest, United, and US Airways -- offer vouchers for the full price difference that a ticket-holding passenger can get a flight voucher if a sale is announced and prices drop below the fare the passenger paid.

Getting the airline to cough up cash or a voucher involves some red tape, as you'd expect. But the only chance of getting anything back from the airline is by tracking fares after you've already paid for your flight -- and nobody wants to do that. So Yapta, it seems, will certainly come in handy.

I've been given a sneak preview of the site and have been testing it out. A key thing to note: For Yapta to start working for you, you've got to plug in exact flight numbers and times. The service searches for fares on that specific trip only; it doesn't search fares for an entire date. That may be good (if you're only be happy with that specific flight) or not so good (if you're flexible with times and are only looking for a cheap fare).--Brad Tuttle, Senior editor