On Aug. 12, a group of 12 fans of the Web browser Mozilla Firefox, which competes with Microsoft’s (MSFT) Internet Explorer, used two-by-fours and rope to hollow out a 30,000-square-foot impression of the brand’s logo in an oat field outside of Salem, Ore. The handmade crop circle wasn’t the first time Mozilla diehards had displayed their support for the brand publicly. In December, 2004, a group raised enough cash to buy a two-page ad in The New York Times to thank those who had contributed to the launch of the beloved browser.

But neither of these stunts was orchestrated by a PR firm or in-house marketing guru. What’s more, the more than 10,000 programmers who are constantly tweaking the open-source coding and performing quality controls on the Firefox browser are volunteers, not employees. And the 60,000 Web sites that have linked to Mozilla’s site to encourage people to download the browser receive no compensation.

It’s this growing community that has allowed Mozilla, a small company with about 60 full-time employees, to compete with juggernauts like Microsoft. “One of our distinguishing characteristics is that we’re a small organization competing on a large playing field,” says Asa Dotzler, community coordinator for Mozilla. He says the company owes its success to its users and their “passion for Firefox.”

The branding success of companies like Mozilla, Pom Wonderful, Craigslist, and others show that you don’t have to be big for your brand to be big. By building a dedicated group of users or customers, small companies can create formidable brand power.