We have come full circle. When Tim Berners-Lee created the Web in the early 90s, his intention was to offer a communication tool to physicists and other researchers around the world. That is a niche audience if there ever was one. After the success of free-for-all social networking sites, the trend is now swinging towards boutique sites where people over 50, hip women or cat lovers get together. MySpace’s domination is not over. In September 2007, it drew 82% of visits among the top 20 social networking sites, the Web’s fastest-growing category, according to a report by research company Hitwise. One in 20 Internet visits went to social networking sites during the month, nearly double the amount of traffic from a year ago.

The popularity and the exploding number of social networking sites are bewildering. According to Chris Anderson’s long tail theory, there is only one way to grow: a larger number of sites targeting a particular audience.

Jeff Taylor, the founder of Monster (www.monster.com), just launched Eons this summer. The site can be described as MySpace for baby boomers. “There is an assumption that people over 50 don’t want to talk online. But we have been surprised that it has grown so fast,” says Taylor who believes that Eons’ strength is to provide a safe and engaging harbor for members to talk, blog and share. Just months after its launch, Eons is attracting 300,000 unique visitors a month.

“Our members answer one question a day which helps them build an interesting profile over time. They get it just as much as younger people,” adds Katie Rae, senior vice president of products at Eons and a veteran of community-building at Lycos and AltaVista. “It is a natural tendency that when groups get too big they splinter.”

At Gather (www.gather.com), Tom Gerace is attempting to lure informed and engaged adults who want to share their life experience in a respectful environment. Partially funded by NPR mainstay American Public Media Group, Gather.com has signed up 130 000 registered members since its launch in November 2005. “We did not expect this breadth of interests,” admits CEO Tom Gerace. “Just like some people used to get their news from TV networks, newspapers or CNN, I believe that there is room for a number of social networks to develop.”

The professional networking site LinkedIn now has 8 million business professionals online. Its growth has not been as spectacular as that of Facebook or MySpace mostly because professionals tend to have less disposable time than teens and college students. “The challenge is getting enough critical mass to make the network useful to its members and monetizable at the same time,” explains Kay Luo, director of corporate communications at LinkedIn.

MySpace is expected to generate $525 million in advertising next year. But delivering targeted demographic group to advertisers seems to be a marketing dream. “Some advertisers were scared of social networking sites because the content is uncontrollable. But they see our site as a safe harbor,” says Jeff Taylor from Eons. At Gather, behavioral and demographic segmenting features allow online advertisers to target members by combining different factors to pinpoint their interest. If nothing else, niche social networks do have a future as advertising venues.

For more proof that micro social networking sites are the next thing, see Ning, a company which bills itself as the “fast and free way to create custom Social Websites”. Now everybody can create their own social network.