In travel industry parlance, these tickets are referred to as "distressed" inventory. They're seats that would otherwise go unused, so airlines cut prices in order to fill them. Their pain is your gain.

Already knew that? Then you're part of a ballooning group of frequent travelers who don't give a hoot about the super-expensive unrestricted tickets. You want the cheapest fare and you don't care if you have to take a red-eye flight or stay over a Saturday night to get it. A recent survey by Topaz International found that business travelers who click online to book these kinds of tickets saved an average of $175 per trip.

Procrastination not for everyone

Yes, there are risks involved. Flights do fill up. Maybe you'll just feel more secure booking your flight well in advance. I'm not saying you can't get a good price. But, in today "new world" of air travel, more and more people are finding out about the last-minute steals you can pull off through "distressed" inventory.

Finding these low fares isn't necessarily a slam-dunk. It takes some savvy. Read on.

Not so long ago, there were only a few sites that offered last-minute tickets. Priceline was an early favorite, and many airlines also offered their own last-minute specials — sometimes also called "weekend" fares — from their Web sites. But then things got complicated. Orbitz came along. And so did a new breed of fare "scrapers" such as QIXO and SideStep that cull the Internet for the lowest price.

"The market for cheap airline tickets is dramatically different than it was just a year ago," says PA Consulting airline analyst Addison Schonland. "But our methods for finding them haven't kept up."

Toss your old buying habits

Don't use an outmoded strategy for finding last-minute fares. You could end up paying more than you need to for your next flight. Here's a look at what's in and out in buying "distressed" inventory:

• Out: A laundry list of travel Web sites. Sadly, many so-called experts continue to believe that if you consult a static list of travel Web sites that have been highly rated, you can't go wrong. Consumer Reports Travel Letter recently recommended such a strategy after reviewing only six travel sites.
   

• In: A dynamic list of travel sites. Inventory levels are constantly changing. Web sites come and go without warning. If you're clicking on the same six sites you were a year ago, or even a few months ago, you might be missing out.

  
  Example: Genia Collins, who works for an insurance company in Norcross, Ga., is always updating her list of last-minute sources — throwing out ones that don't work and adding new ones. In order to find an appealing last-minute fare, she starts at Hotwire, which generally gives her a good idea of what the bargain-basement fares for her itinerary ought to cost.

  
  "Then I go to Orbitz, and I see if there's a comparable fare," she says. Why Orbitz? Because unlike Hotwire, you know which airline you're using — and you can exercise greater control over your itinerary. Orbitz also carries inventory from more than 450 airlines and can give you more than two billion possible fare combinations.

  
  Collins' next stop is the Web site of the airline that's offering the low fare. If the same price is available, she often can collect bonus frequent-flier miles and avoid the $10 Orbitz booking surcharge. If she's unhappy with the results, Collins surfs to Expedia, which she says, "offers some fantastic deals lately not available anywhere else." And if that doesn't work, she'll click on CheapTickets or even go to Priceline and make a bid.
   

• Out: Dumb fare searches. The conventional wisdom is to canvas every travel Web site for a last-minute fare. The more searches, the merrier.
   

• In: Smart searches. Online travel agencies ink deals with different carriers to carry their tickets. For example, Travelocity offers special access to fares from American Airlines; Expedia has cut-rate Northwest Airlines tickets and CheapTickets offers an abundance of Delta Air Lines inventory. Ticket availability fluctuates by season, demand and even time of day. Don't go looking for a last-minute ticket in the wrong place. Go where the inventory is.

  
  Example: Enda Carey, a systems analyst in New York, knows that on certain trips — say, New York to Buenos Aires — American Airlines will offer the best last-minute fares from its Web site. He recently paid $426 for a flight to Argentina (a 14-day advance ticket costs $556). What's the point of spending hours online, querying every single site that offers last-minute deals, when the American Airlines site has the best tickets?
   

• Out: Web-only fare searches. One of the oldest assumptions — false, it turns out — is that all the last-minute tickets are online. The National Business Travel Association, a trade group, was so convinced that the lowest fares were on the Internet that it asked the U.S. Department of Transportation to investigate Web fares on Orbitz. The implication is that by booking offline, its members were missing out.
   

• In: Inclusive fare searches. Travel agents may have had their commissions eliminated by the airlines, but they can still sometimes find great last-minute deals. Don't count everything offline out. Remember the Topaz survey? It found that the even though business travelers saved money in the short term, they wasted money in the form of longer connection times and inconvenient itineraries in the end.
   

  Example: When Patrick Proctor wanted to surprise his wife with a trip to Hawaii for her 48th birthday, he enlisted the help of a travel agent, who helped him find a fare sale on American Airlines for $346.26 per person. The year before, his tickets to the 50th state had cost $950 per person. "It was a deal of a lifetime," says Proctor, who manages a glass company in Bartlesville, Okla. His agent had been watching the prices on tickets to Hawaii, and the moment American Airlines decided to run a sale, she called him.

It helps to think of last-minute tickets the same way an airline does. Distressed inventory is the proverbial carriage that will turn into a pumpkin at midnight. Use it or lose it. The airlines really don't care who sells the tickets, as long as they're sold. So they have no incentive to maintain any kind of status quo — only to dump the tickets before the flight takes off.

That's why checklists don't work and why you can't limit yourself to just one medium. Because the airlines selling these tickets don't, either.