Imagine you're a farmer in India with a crop of potatoes to sell. Typically, you go to a marketplace called a mandi and get the best price you can from a local middleman, who will then sell them to another middleman.

What will the potatoes ultimately sell for? Is there a better price somewhere else? No way to tell.

A father and son based in New Delhi want to expand farmers' selling options by bringing the mandi to smartphones. The idea came to Sanjay Agarwalla while he was consulting with telecom and consumer goods companies looking to expand into rural India. He noticed that even as his clients eyed these new markets, no one was thinking about how to help farmers increase