You shopped around to get the best deal on a new computer. Two weeks later, you see it on sale for 10 percent less than you paid. Before you do a slow burn, find out if your card offers price protection.

How it works: If you discover something you've already purchased at a lower price within the given time period, which in some cases can be up to 90 days, the card will refund you the difference.

Once again, it pays to read the fine print. Obviously, there is a time deadline and it must be exactly the same item. Some credit card issuers will also stipulate that the lower price must be advertised in writing. For instance, Citi's price protection service requires that you see the item advertised in print at a lower price within 60 days of purchase.

There may also be a cap on the reimbursement amount. For instance, the Continental Airlines Presidential Plus Card from Chase limits the rebate to $500 a claim and up to $1,500 per year.

And, as with all of these benefits, you have to use your card to buy the item in the first place.