Image: Cashier & customers at checkout © Andersen Ross, Getty Images

Related topics: debt, credit, credit card, smart phones, Melinda Fulmer

If you think U.S. consumers were huge impulse buyers before the recession, just wait: Mobile-phone companies, banks and credit-card companies want to speed things up so people can simply swipe their cell phone to pay for everything from cups of coffee to cruises.

Banks such as Citigroup and a technology startup, Bling Nation, which ties its tags to PayPal accounts, have in the last year launched radio-frequency identification (RFID) payment stickers to attach to your cell phone. They will allow customers to rack up charges without even carrying a wallet.

And over the next few years, companies including Apple, Samsung and Nokia will incorporate special near-field communications (NFC) chips in smart phones that will let shoppers make purchases simply by tapping their phone against a terminal - no sticker required.

Mobile analyst Leif-Olof Wallin of Gartner Research says he expects half of all mobile phones to have the chips by 2015, pushing this tap-and-go payment into the mainstream and getting us one step closer to using our phones in almost every aspect of our lives.

The downside of fast money

But while the mobile wallet sounds incredibly convenient, experts say it could pose a potentially big credit risk, especially to younger consumers who may swipe and forget -- and rack up big debt.

"There is certainly a disconnect when it comes to spending and using a credit card versus cash," says Bill Hardekopf, the CEO of and author of "The Credit Card Guidebook."

When you have to reach into your wallet and fork over several bills, write a check or even sign a credit-card receipt, you're closer to the financial pain, he says.

"Your mind says, 'Do I want to do this? Is this item worth it?'" But will that happen with something as painlessly quick as a swipe of the phone? Maybe not, he says.

Banks and other providers of this technology downplay this risk, saying it is just the next evolution in personal finance: Just as many of us have booted checkbooks from our wallets and purses, those old-fashioned plastic cards are the next thing on the way out.

"In five years, you're only going to need to think about your phone," says Mung-Ki Woo, the head of MasterCard's mobile payments division. "Everything else will be inside your phone, including your keys."

Revving up the spending machine

Why are credit-card companies and others so eager to get us paying with our phones? The answer is simple: We spend more.

While Citi and several other companies declined to say how much more mobile-payment users spent, market-research firm Forrester Research says that consumers who express interest in mobile payments spend 22% more on average than people not interested in it. And they were more likely to make frequent purchases.

When PayPal account holders were offered the chance to use its Bill Me Later credit service on eBay, the size of purchases doubled, says Anuj Nayar, PayPal's director of global communication.

The beginnings of a mobile revolution

The technology for this kind of swipe-and-go mobile payment has been in place for years, analysts say. It has already been used for public transportation and other types of purchases in Europe, Japan and South Korea.

But until last year, mobile payment in the U.S. was virtually nonexistent, outside some purchases made with a credit-card number on a smart-phone browser, or through applications from Amazon or eBay.

Fewer than 6% of U.S. adults online have used mobile payment, according to a report released last summer by Forrester. But, according to that report, 15% of adults are "interested" or "very interested" in using their mobile phone to pay for items in a store rather than whipping out plastic.

Enter Bling Nation, a Silicon Valley startup that partnered with PayPal last summer to provide payment tags for phones that are now being used in about a dozen cities in six states, mostly college towns.