That's clever. The Forbes story mentions the use of google advertising done directly by dropbox, but noted they found it ineffective. However that probably referred to the uptake of paid subscriptions? "They toyed with advertising. “That’s what you’re supposed to do: hire a marketing guy, buy Google AdWords,” says Houston. “We sucked at it.” It was costing them $300 to hook one sign-up.". http://www.forbes.com/sites/victoriabarret/2011/10/18/dropbo...