The research, released this week, even assigns a dollar value to e-mail interaction with an employee's managers. Among the group studied, several thousand consultants at IBM, those with strong links to a manager produced an average of $588 of revenue per month over the norm.

The results represent an early attempt to understand the value of the broadening variety of personal connections afforded by the Web. Users of social media rack up LinkedIn contacts, Facebook friends, and Twitter followers by the hundreds, if not thousands. But figuring out how big a difference all those contacts make in a person's life, financial or otherwise, is a far murkier matter.

That's why leading tech companies, including IBM, Microsoft, and Yahoo!, are hiring economists, anthropologists, and other social scientists to map and classify new types of friendships