It seems contradictory: Yes, you want to use that gift card quickly. However, you don't want to buy just to buy.

If you really want to make a smart purchase, "wait for something that you actually really need or want," says Mendelsohn.

Still stuck with an aging gift card and don't know what to buy? Or maybe the card isn't to a store you love?

Either regift the card or use it to buy a present for someone else, says Mendelsohn. And take the money you free up and treat yourself.

"It's a great way to not spend your own money," she says.

They also make a great tool to save money toward a big purchase, says Mendelsohn, whose family used gift cards to pay for two computers.

"Particularly with kids," it's a great way to impart the lesson of saving for a goal, she says. "Even though it's a gift card, it really teaches them -- you can accumulate and get something really meaningful."