One revenue model that is a natural for social networks is what’s often referred to as two-sided platforms: That is, your platform (your social networking site) serves the needs of two (or more ) sides within a niche. It brings two groups with a common focus and lets them interact in a way that benefits both sides.

Unlike advertising (which tends to be a one-way conversation) or pay-for-access (which tends to happen within a single group) two-sided platforms allow marketers or producers a chance to participate in the community in a creative and productive way.

Facebook’s Pages are an example of this model at work (though they don’t charge — yet). Coke has more than 4 million Fans on Facebook, and in a recent study 40% of consumers report having “friended” a brand on Facebook and/or MySpace.

For smaller niche social networking sites which are built around people’s passion, this kind of revenue model makes even more sense.

Cork’d, Gary Vaynerchuk’s wine-based social networking site, does this as well, by bringing together wine lovers with wine producers. In an industry where people routinely spend their vacations touring wineries and meeting vintners, this is a perfect mix.

How often does the average wine lover get to take a trip to visit their favourite winery? When they do, it’s about meeting and interacting with the owner and vintner, getting the inside scoop on next year’s release, perhaps getting a deal or just feeling more connected with something you enjoy so much.

Cork’d offers wineries the chance to create “Verified” profiles for $999. Once they get verified, they can start communicating with their fans, manage their online listings, link to their site and more.

Note that this isn’t the same as an advertising model: the advertisers aren’t limited to static banners or ads on the site: they are treated as a member of the community, and the value for them comes in being able to interact with people who want to interact with them.

A bonus here is that this can help solve the problem of marketers spamming your members by giving them a legitimate and transparent role in the community.

What’s your community’s passion? Who are their heroes? Who wants the chance to have a discussion with your community? Who wants to be their fans?