Google (Nasdaq: GOOG) is counting on you to leave home without your wallet before you would ever forget your smartphone. By "you," I mean the 65% of people between the ages of 18 and 34 who told MasterCard earlier this year that they feel more naked without their phones than without their wallets. For those folks, Google has the perfect solution: Google Wallet.

Google Wallet is a service that can be accessed by smartphones powered by Google's latest version of its Android mobile phone operating system. It allows shoppers to pay for their purchases by just bringing their Google Wallet-capable phone into proximity with a Google Wallet reader. To do this, it uses what's called near-field communication technology.

Right now, Google Wallet works only with Sprint Nextel (NYSE: S) and the Samsung Nexus "S" smartphone running Android OS version 2.3.4, and only PayPass-enabled Citi MasterCards may be loaded into it. Google is trying to also get Visa, American Express, and Discover Financial Services on board.

Google introduced Wallet with little fanfare in September, but it's now starting to turn up the volume with a series of road shows. It will be demonstrating Google Wallet in New York City, Chicago, San Francisco, Los Angeles and Washington, D.C., between now and mid-January. The demos will take place at various retailers, including Duane Reade, Jamba Juice, Walgreens, Peet's Coffee & Tea, and Foot Locker.

Google Wallet can also be used to download and use coupons, merchant loyalty cards, and gift cards into their phones. Other uses Google wants to incorporate are the abilities to store boarding passes, tickets, and ID cards.

But AT&T (NYSE: T), T-Mobile, and Verizon (NYSE: VZ) have not been sitting idle. Those companies have been supporting another mobile payment network called Isis, which already has support from Visa, American Express, and Discover, as well as MasterCard.

The systems for using near-field communications are just being implemented, but the potential for this technology is huge. Telecom specialist Juniper Research believes that by 2015, global NFC transactions will be close to $670 billion.

I have my phone and my wallet, but I can't find my keys. Is there an app for that?

To learn more about near-field communication, check out this free report prepared by the Rule Breakers team at The Motley Fool: "Your Credit Card May Soon Be Worthless. Here's Why..."

Fool contributor Dan Radovsky owns shares of AT&T. The Motley Fool owns shares of MasterCard and Google. Motley Fool newsletter services have recommended buying shares of Visa and Google and creating a write covered strangle position in American Express. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.