Image: Airport check-in © Digital Vision, Getty Images, Getty Images

4. Checked-bag fees

Airlines collected about $3 billion last year in fees, and they're on track to rake in even more this year. Before 2007, most passengers never paid these fees, since two checked bags were included free with every ticket. Now, though, virtually every airline charges $25 or more per bag. (The exceptions are Southwest, which still allows two free checked bags, and JetBlue, which allows one.)

If you're hauling a bunch of holiday loot, you may encounter even more egregious fees -- the ones for overweight and oversize luggage. You could pay $100 or more each way. (AirfareWatchdog has a chart of airline bag fees here.)

With the plethora of free shipping offers available during the holidays, it often makes a lot more sense to have your presents shipped by the retailers to your destination. Another option is to focus on small gifts that can be easily packed in your carry-on bag. (That means no bottles of booze, jars of jelly or other liquids that exceed 3 ounces.) Ask those giving you gifts to consider your packing restraints.

If you do transport gifts in your luggage, carry-on or otherwise, don't wrap them. It's a waste of time and money, since airport security may tear off the wrapping to see what's inside.