Those of us who were leaning toward Delta Air Lines because of its policy of allowing a free first checked bag can now abandon any favoritism. As of December 5 (just in time for the holidays!), it will start charging $15 for the first check bag. That figure is pretty much what everyone's charging these days. Only upstarts like JetBlue and Southwest don't.

The news, though, brightens in a few quarters. Simultaneously, Delta has decided to halve its fee for a second bag from $50 to a more sensible $25. Not many of us check two bags, though, so the net effect will still be negative for most casual travelers.

The major American airlines, now that they've got you on the hook for your checked bags, are relenting on their fuel surcharges. Delta and Northwest are eliminating their fuel surcharges. It's about time, too, since it's gotten pretty hard to defend them. The price of oil peaked back in the summer but is now less than half what it was at its peak, and in the past month, it has fallen about $30 a barrel.

So you buy an airfare at a ridiculous price -- or even a good one. And a week later, the airline decides it hasn't sold enough seats. Rather than fly an empty plane, which would cost it money, it slashes the prices on seats. Come the day of the flight, you turn to the person sitting next to you and learn, to your disgust, that they paid $200 less than you did.

What can you do? Well, by the time you're on the flight, often nothing. But if you discover you've paid more than you had to before you have used the ticket, you can usually petition the airline for the price difference. Usually, that refund comes in the form of a voucher that you use for future travel, but that's still money you don't have to spend later on.

But, surprise! Some airlines have a nasty trick up their sleeve. Many charge obscene change fees since, the way they see it, they have to pull your old ticket and issue a new one to give you the better price. That means that for domestic flights on U.S. Airways, Continental, and American, the price has to drop by more than $150 in order to give you an ultimate benefit. But plenty of other airlines don't charge any fee at all (JetBlue, Alaska, United), or their fee is small enough to give you pretty good chances (Northwest's is $50, AirTran's $75). The fees are usually steeper for international flights, but then again, the price drops stand to be higher for those, too.

After you book a flight, you could keep returning to the airlines' websites to double-check the rate status of your booked flights. That will work. But one of the lesser-known airline booking sites, Yapta, keeps tracking the price of the stuff you've bought, and if it descends past the point where you can actually make some money back, it alerts you by e-mail. (The site, like Hotwire's Trip Watcher and Farecast, will also keep an eye on rates for flights you haven't bought.) Every bit helps, right? Maybe the amount you save will pay for a pack of peanuts. Barely.

Hedging fuel costs sounds confusing, but it's nothing new. Some airlines, like the budget model Southwest, have managed to claim a profit in no small part because their masters were clever enough to buy most of its fuel when it was still sensibly priced. That can work out really well if gas prices go up, because those smart airlines will still be paying an older, lower price. Some experts think Southwest has saved $3.5 billion by doing this since the late '90s.

United Airlines, which has a management as sharp as a box of hammers and aging seating about as soft, thought it could imitate Southwest by getting into the hedging game, too. But, whoops! Timing is everything. It got in way too late, as the market prepared to peak. Prices went down. And right now it's paying almost $13 more a barrel than oil is actually worth, which could rack up as much as $544 million in boneheaded, unnecessary losses.

It's a lot like the guy down the street who bought his house a year ago for $400,000, only to find in this self-correcting market that it's now worth about $250,000, which everyone in the neighborhood knew was a more realistic price all along. He intended to flip it, but now he's got to live in it. Of course, if gas prices go back up a bit, United's loss may be mitigated slightly.

Just when will fliers rebel against all the cost-cutting at the airlines? Probably never. We will just keep taking the charges in stride. If anything is going to make us stop flying, it is that costs are going up and people just don't have the money to travel as much these days.

Today's news about Northwest adding up to an $80 surcharge on flights is bad news, but has become pretty typical these days. The bigger headline may be what US Airways is trying to do, as reported by the New York Times: charge for coffee and other beverages. The hidden lead here is that the fee was originally announced June 12 and did not cause too much of a fuss, even though it marks the first time a major airline has stooped to these cost-cutting depths. It is only surfacing now because the union that represents flight attendants is complaining about it.

Even the company seems a little skeptical that they'll be able to pull it off. Officials are apparently telling flight attendants that they can be liberal in applying the new charges, meaning that if anyone complains, they can just placate them with a free drink.

I can imagine how those conversations will go:

Deal of the day for Wednesday, March 26th, 2008- If you are planning to fly Northwest Airlines between April 1 and June 14, 2008, you can save $50 off of a booking of $250 or more. In a joint promotion with Paypal, the airline will refund $50 of this booking if paid for via Paypal, Ebay's on-line money exchange system.

To qualify, you'll also need to be a member of the airline's frequent flyer program, WorldPerks. There is no charge for this program, though. The refund will be credited to your Paypal account within 6-8 weeks. Tickets must be purchased in the U.S. through nwa.com.

Haven't used Paypal before? It's a very convenient service with a well-designed interface. I use it to buy from Ebay and Amazon, and collect freelance writing fees through it when the client declines to pay the invoice by mail. Paypal takes a pretty deep cut of my incoming money, though, so I prefer to use it only on purchases. Your account can be tied to a credit card or checking account.