A single button could solve Facebook’s revenue problem

October 11, 2012, 6:06 PM UTC

FORTUNE — It was only after Facebook went public that attention to its revenue troubles reached critical mass. And it was only after that ill-starred IPO that people began asking — in earnest and at full volume — how the company could possibly make money on mobile platforms, where it is nearly impossible to serve ads.

Facebook (FB) might be onto the beginnings of a solution with its new, Pinterest-like “want” button, which it has rolled out as a test. Facebook has teamed up with seven retailers including Pottery Barn, Victoria’s Secret, Neiman Marcus and Fab.com for its new “Collections” feature. It’s “a fairly transparent hedge against Pinterest,” says Todd Wasserman of blog Mashable.

But it could wind up being much more than that. With a billion users, Facebook has amassed a gigantic number of consumers in one place. But so far, the main way it has made any money is by serving up ads. And online ad rates are falling, which means that revenue-per-user is falling, too. The Collections feature has users themselves sharing the stuff they like with each other — hitting the “want” button puts pictures of desired products on the news feeds of friends, who can then hit their own “want” button, or even make a purchase via Facebook.

For now, Facebook will not be taking a cut from those purchases, but rest assured that if the tests prove successful, it will. And that could prove to be a big generator of revenue.

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It also will allow Facebook to rely less on the often-cheesy, sometimes spammy ads that it runs. And it makes the best use of Facebook’s sharing capabilities, which is after all, is what social media is all about. If your friends like something, there’s a decent chance that you’ll like it, too. And it won’t be an advertiser directly pitching a product, but just a friend saying that he or she likes that product.

The appeal of Pinterest is somewhat mysterious to those who don’t use it. But it allows people to gather together in one spot images of all the things they like — fashions, home-decorating ideas, cooking tips, etc. But you have to become a Pinterest member to use it. Most people who are likely to do so are already on Facebook, and are already hooked up with most of their friends and relatives there.

Meanwhile, eBay is getting into the game as well. It has launched “Feeds,” which works similarly to Pinterest and Facebook’s Collections, but with products that are on the site and available for sale. It “brings the products you want right to you, as opposed to the other way around,” eBay says.

In retrospect, it’s surprising that this idea took so long to catch on. But social media tools had to advance to the point where such sharing was made simple, and businesses had to get fully used to the idea that their best salespeople were often their own customers.