Niti Bhan studies business strategy for Africa's informal markets: the small shops and stands, skilled craftspeople and laborers who are the invisible engine that keeps the continent's economy running. It's tempting to think of these workers as tax-dodgers, even criminals -- but she makes the case that this booming segment of the economy is legitimate and worth investing in. If we do, she says, we might create thousands more jobs. "These are the fertile seeds of businesses and enterprises," Bhan says. "Can we start by recognizing these skills and occupations?"