Turning your cell phone into a wallet

Mobile commerce has finally arrived, with PayPal, MasterCard, Cingular, and a host of startups fighting over the $24B cash-on-cell-phones market.
By Michal Lev-Ram, Business 2.0 Magazine writer-reporter

Business 2.0 Magazine) -- When Amazon.com engineer Gaurav Oberoi went on vacation to Europe with friends in 2004, they decided not to worry about who paid for what until after the trip.

But that meant recording expenses in a paper notebook, typing the numbers into a spreadsheet, and e-mailing it back and forth. "Splitting bills can be a relationship killer," Oberoi says.

He knew there had to be a better way. So he and fellow engineer Chuck Groom quit Amazon.com (Charts) to build a company that tracks informal loans - a market the two dubbed "social money" - via cell phone.

Their Seattle startup, BillMonk, launched in January. Its free service sends reminders about what is owed to whom; BillMonk expects to cash in by charging for premium memberships that let you settle up by phone. More than 7,000 users have signed on already.

"The economy of informal debts is huge," Oberoi says. "All we're doing is making this invisible market visible, then monetizing it with payment options."...for more of the story from CNN Money