Delta, which will soon be the world's largest airline (after it merges with Northwest) has increased baggage fees once more. Although the first checked bag is still free, a second will now cost $50 up from the previous $25 (that's assuming that it's not overweigh or oversized, in which case additional fees kick in). In addition, a third checked bag now costs $125 up from $80 and a bag weighing 51 to 70 pounds will cost an additional $90, up from $80. Delta claims that less than a fifth of its passengers check a second bag, and remember that these policies only apply to domestic flights.

Oh, and we thought this was very interesting: Micheline Maynard, writing in Thursday's New York Times, quotes a Delta frequent flyer program spokesperson who notes that the number of miles issued by Delta had grown by 24 percent from 2004 to 2007, but the number of frequent flyer seats has not grown. "The capacity is just not there," he says. How refreshingly honest. That means it's 24 percent harder to find a free seat.

We're assuming that when the merger takes place, these higher Delta fees will supplant Northwest's baggage fees. If you haven't already, take a look at our updated baggage fees chart.