By limiting its online community to diehard users, the software maker has marshaled a volunteer army of expert customer service reps.

Unlike many other companies, however, Intuit seems to have figured out a way to benefit from social media. Its insight: Rather than inviting the whole world, the accounting software maker funnels only diehard users of QuickBooks to a site where they can exchange truly helpful information. For customers, that means quicker answers to problems. For the company, this volunteer army means less need for paid technicians.

Customers were not only asking technical questions, they were often outshining Intuit’s own tech support staff by answering 40% of the queries themselves.

Since the latest edition of QuickBooks went on sale last October, traffic on its channel has tripled. At any time, 70% of customer service questions are answered by other QuickBooks owners.

Summary: The social aspect of the program seems to have helped sales. The company has sold 1 million units of QuickBooks at $200 apiece, boosting the software’s market share by 4 points, to 94%. All that free tech support is saving Intuit money as well.