Gerald Gorman, who runs online businesses like Lawyer.com, pays Google (s goog) $100,000 a month to place ads near search results and on Google's partner sites. While the ads have proved effective at attracting customers, their growing price tag has led Gorman to look around for alternatives.

In the past, Gorman would have been out of luck. That's because, despite the internet's rapid growth, most small and medium businesses had few viable online ad options beyond Google or Bing.