A few years ago, Nathan Eagle had a big idea. What if millions of people in poor countries—people who couldn't find work in their local economies—could become a remote workforce for organizations all over the world? And what if, instead of traveling to do such jobs at call centers or other outsourcing offices in big cities, they could do their work quickly, reliably, and easily through text messages on their mobile phones?

Eagle founded a small startup, Txteagle, in Cambridge, Massachusetts, to put the idea to the test. It has struck deals with mobile-phone carriers around the world to pay workers in credits for mobile airtime. In many places, that's as good as cash.