According to a new McKinsey report, “research suggests that seven sectors alone could generate more than $3 trillion a year in additional value as a result of open data, which is already giving rise to hundreds of entrepreneurial businesses and helping established companies to segment markets, define new products and services, and improve the efficiency and effectiveness of operations.”

That’s a mighty big carrot to open up public sector data to the public, keeping in mind potential privacy, political and national security consequences of doing so carelessly.

A growing number of open data entrepreneurs are mining these embryonic markets, finding fertile soil using different business models that focus on adding value to a national resource: data collected for the people, released back to the people.