PayPal has created an iPhone application along with Bump Technologies that allows iPhone users to pay one another by using their cell number or by bumping phones together. (Unfortunately its name could be a little snappier than PayPal's Send Money and its counterpart, Collect Money.) The same app can be used to swap other information.

Bump Technologies provides the bumping/swapping information immediately, and one uses PayPal with a cell phone number and PIN. The application tools also allow people to split up checks or factor tip or tax. PayPal previously used a text-message service but it never seemed to catch on. Now PayPal is working on a merchant application so users can use their phone to pay for goods -- even with a bump. The new app is available in 18 different languages for use globally.

PayPal's mobile transactions have more than quintupled from $25 million in 2008 to $141 million in 2009. Not to be left out, credit cards Mastercard, Visa and Discover are also using mobile payment platforms. Nokia also is working on a payment platform for merchants that bases fees on transactions.

But so far, the phone bumping seems to have everyone else beat. Why? Because even though we can send money to one another through text or phone numbers, the idea of having to bump one's phone gives it a little bit of a human component -- that slight edge of human interaction that makes things real.

The only problem is that both sides of the transaction must have iPhones and the same PayPal application. If not, you might have to divide a check the old-fashioned way -- with cash.