According to Juniper Research report in 2008 the total value of the user-generated content (UGC)market - comprising social networking, dating and personal content delivery services - will rise from nearly $1.1bn in 2007 to more than $7.3bn in 2013, with social networking overhauling dating to become the largest revenue- generating segment by 2009.

What is clear is that most of the major protagonists have mediocre if any revenues to date and are certainly a million miles from profit. In fact, they appear more like charitable concerns (Twitter and Wikipedia in particular) than businesses. Why is this and what might change?
Although striving for the lucrative ad dollar the UGC sites are often poorly profiling their members from an advertising perspective, making the choice for advertisers difficult. It's clear that retrofitting any kind of member-related fee is almost impossible so where do we look for inspiration?
Just like with any emergent technology the industry that is first to develop a commercial model is the adult sector.
This model has transferred over to dating sites as well where there is a element of free "tease" but to be a fully- active member and gain maximum benefit there is a low subscription charge. The objective is to get to engagers rather than browsers - folks who actively contribute.
One model being explored by Wikipedia is to charge a nominal fee for editors and approvers rather than browsers. For Wikipedia it will limit malicious or frivolous editing and the same could be true for similar sites.
If your goal is advertising then make your site interest- specific so that advertisers can target their most interested demographic. The rates for such advertising are higher and more valuable. Mobile social networks will make use of subscribed geolocation services increasing real world interaction by identifying those close to you. For most the route to revenue is complex but it's clear that relying solely on advertising is risky - if you build it they may not come...

Steve Everhard is associate director at Grant Thornton Entrepreneurial Advisory