John Hagel and Marc Singer's new book, "Net Worth: Shaping Markets When Customers Make the Rules" (HBS Press, 1999), outlines a major $20 billion business opportunity driven by the rise of the Internet. "Infomediaries" -- companies that gather consumer information and find willing buyers for it -- will capture consumer behaviors and preferences, act as consumers' agent, protect them, and share their data with vendors.
Banks, brokers, trust companies, and credit bureaus are potential infomediaries. However, because large economies of scale are required, few companies will succeed. Nonetheless, all firms marketing to consumers will be affected.