It may be hard to imagine a credit card company -- or most other for-profit businesses, for that matter -- trying to wring a few additional dollars out of customers. But believe it or not, it's happening with many card issuers. Here are some tricks to watch out for:

  • Card companies are communicating more. If you send in a late payment on one card, some of your other cards may begin charging you a higher interest rate. Similarly, if you're approaching your credit limit on one card, you may see rates rise on one or more of your cards. Higher rates are bad, bad, bad for those who are mired in credit card debt. (Fortunately, you can get out of debt.) Basically, card companies want to charge you as high a rate as they can, so they're looking for reasons to hike your rate.

  • Late-payment fees are becoming more forceful, sometimes levied if you're only a day late. These can be a big deal -- some cards' fees approach $40! Making matters worse, you may not have as long to pay your bill as you used to have -- many card companies are shortening the turnaround time.

There are many other card tricks you should know about -- read all about them in our Credit Center. And while you're there, consider taking advantage of a chance to get copies of your credit report from all three agencies in one fell swoop and for one special price. Review your credit report and you may find some errors worth fixing -- perhaps some errors that are keeping you from getting the best interest rates possible when you borrow.

Here are some eye-opening articles on credit cards and debt:

Oh, and if this is making you think that credit-card-related companies might be good to invest in, look into firms such as MBNA (NYSE:KRB), American Express (NYSE:AXP), Capital One Financial (NYSE:COF), and Citigroup (NYSE:C). Or let us recommend some stocks and funds for you, instead.

Finally, talk about all things credit-related on our Consumer Credit / Credit Cards discussion board -- or just pop in to be inspired by people who are beating down their credit card debt successfully.

Longtime Fool contributor Selena Maranjian does not own shares of any companies mentioned in this article.