Online marketplaces for independent workers such as Upwork (formerly oDesk) and Elance are more popular -- and profitable -- now than ever before. Both sites report about 1.5 million registered contractors, and oDesk announced today that each year since 2007, it's doubled revenue.
Elance has maintained similar growth. Speaking with Mashable, Elance CEO Fabio Rosati said, "We have reached a tipping point where the early adopters have convinced everyone else that this is the way to go. Our first quarter this year will be the fastest growth we've had in our company's history."
What's behind the massive growth of these online marketplaces for independent workers?