"The ever-changing world of airline fares and fees is getting a little more confusing -- but maybe a lot cheaper -- thanks to the newest travel perk: free baggage check with an airline's credit card." That's from The Detroit News, which takes at look at some of the latest gimmicks being rolled out to entice consumers to sign up for airline-branded credit cards.

Continental and Delta are among the latest to waive checked-bag fees for customers booking using the carriers' branded credit cards. The offer covers up to as many as nine people traveling on the cardmember's reservation, allowing each of those to avoid bag fees that start at $25 per bag.

The News writes "it sounds like a good deal, but there's a catch: another fee. In the case of Continental, it's the $85 annual fee for the OnePass Plus card, and for Delta it's $95 for the Gold Skymiles card."

"Card issuers are raising more money by getting annual fees, and they're using the rewards as an add-on to justify the fee," Bill Hardekopf, CEO of credit-card comparison site LowCards.com, tells the News.

Of course, travelers can quickly recoup that fee by avoiding bag fees on as few as two round-trip flights. On the other hand, the perk is unnecessary for others.

For example, elite-level frequent fliers are exempt from checked bag fees. Or, as the News points out, "if you don't travel with luggage often enough -- maybe once every other year -- it's cheaper for one or two travelers to pay the baggage fees instead of shelling out for annual credit card memberships."

Either way, expect airlines to increasingly turn to special credit-card perks in the future. Daniel Ray, editor in chief of CreditCards.com, predicts to the News that the trend will accelerate as carriers look to build customer loyalty while at they also broaden their a la carte fee structure.

SHARE: Do you have an airline-branded credit card that offers such perks? Do you think they add value? Or, do you think they do not justify the annual fees? Share your thoughts.