Jeff Gelles: Interactive children's books for the iPad generation

Kartik Hosanagar and Prasanna Krishnan have the earmarks of a power couple. At 36, Hosanagar is a professor at Penn's Wharton School, cofounder of Yodle Inc., an online marketer, and an angel investor in a dozen other start-ups. Krishnan, 34, has done stints in tech development at Comcast, venture investing in Silicon Valley, and management at Jetsetter, a travel website.