Social networking habits come in many forms.

Unless you have been hiding under your 24-inch monitor, you almost certainly know about the most common of these — Facebook, MySpace and Twitter.

But they’re far from the only ones. Plenty of people supplement a Facebook addiction with additional social networking habits; others shun the leading brands in favor of lesser-known options. If you’re tired of Facebook, just don’t get Twitter or have decided to leave MySpace to the teenagers, then you might think about exploring another social networking service.

If you do, just embark on the endeavor with the following in mind:

A social network is only as lively as its members. Even if a site looks interesting, it won’t offer much unless you’re able to connect with real-world friends or meet new ones. There’s a reason Facebook keeps growing: There’s a fair chance you’ll find a lot of people you know there.

Review the network’s privacy policies and your personal settings to ensure you’re not sharing more information than you intended.

Participating in a social network — connecting with friends, building your personal profile, adding photos and various likes and dislikes — requires an investment of your time. You want that investment to matter. Though it may be tempting to join every upstart social network out there, be wary of startups without much of a following, as you never know if they’ll be around a year or two from now.

Here’s a selection of nine social networking sites to explore:

Ning: Maybe you don’t like the social networks out there, and you want one of your own. With Ning, you can have just that. Ning lets you create your own social network, much as do-it-yourself webpage creators let you create websites. You can choose from prefabricated themes and then add other features, like video, chat, blogs and various applications.

LivingSocial.com: At LivingSocial.com, you’re able to catalogue your interests, then glean recommendations from friends. If you’re into beer, for instance, there is a special community for you, where you can rate and review beers. Ditto for books, movies and more.

Dopplr: Serious travelers love Dopplr for the way it connects them with other international travelers interested in sharing travel plans and recommending places to eat, visit and stay in cities from Amsterdam to Zurich.

DailyBooth: Not much into words, even if it’s the meager 140 characters permitted in Twitter posts? Then DailyBooth may be for you. The website is all about connecting to people with snapshots. As at Twitter, you can “follow” other people, and they can follow you.

Change.org: Yes, you can actually do good through social networking, as is clear from a visit to Change.org. The website helps people connect with nonprofits and causes.

Goodreads: A community for book lovers, Goodreads lets you connect with friends to find out what they’re reading, suggest books and track what you’ve read and what you’re planning to read.

Kaboodle: Shopping online doesn’t always mean shopping alone. If you want to commune with other dedicated shoppers, then check out Kaboodle, where you’ll be able to share shopping lists and get recommendations from people who like the same products and styles as you.

SportsMates: For diehard sports fans, SportsMates provides a social network that’s all about connecting around teams and sports, from gymnastics to rugby and beyond.

CafeMom: As the name suggests, CafeMom is all about connecting with other moms and moms-to-be, with posts like “How do you get your kid to help?” and “Mowed the backyard … still not in labor!”

Alan Hoffman may be reached at netscan@alanhoffman.com.

Of late, Michael Rubin’s life has been transformed by a website that lets anyone create their own online social network within minutes free of charge. The site, called Ning, allows the mild-mannered family man from Santa Cruz, Calif., to inhabit more personas than a superhero as he dashes heroically between several of his social networks.

Mr. Rubin used Ning to start a loyal customer base for his chain of “paint your own ceramics” studios and foster a community around a book he’s written about digital filmmaking. During a past job as a product manager for Netflix, Rubin created a Netflix fan community on Ning where he still interacts with fellow film aficionados. Outside of work, he has a private Ning network for his extended family – though he rues that his older relatives aren’t up to speed on Ning features such as photo uploads, video-sharing, forums, personal profiles, and blogs. Rubin even developed a Ning site for a babysitting co-op in his neighborhood.

“Once you know about Ning, [you wonder], ‘how many places can you apply this?,’ ”
says Rubin. “Over the spring of this year, I experimented: I must have made six or seven different communities of different sizes.”

Ning is at the vanguard of a coming shift in the online world. Before, social networking has mostly been contained within sites that are nations unto themselves. You have to sign up to the likes of MySpace, Facebook, and Hi5 to get a passport to fully roam those territories. Once inside those borders, each citizen is confronted with a one-size-fits-all “horizontal” landscape that covers all sectors of society and every demographic, and where each page follows the same basic template. But Ning offers an alternative: It’s an open platform for thousands of individual-looking niche “vertical” networks.

“Ning will continue to gain interest as more and more people get involved in social media and social networking,” says Robb Hecht, an expert on social networking who operates IMC Strategy Lab, a media consultancy in New York. “Previously it was LinkedIn and Facebook and MySpace where the container – if you could call it that – was something that you could become a part of, but you couldn’t actually own, or run, or direct.”

Launched in 2005, Ning, which means “peace” in Chinese, now hosts 358,000 networks. Among them: A gathering point for rock-band roadies, a group to assist Iraqi refugees, a hub for enthusiasts of unmanned aerial drones, and the official David Hasselhoff fan site. Some Ning pages caters to pornography – this is the Web, after all.

If you hadn’t heard of Ning – and most people haven’t – it’s because you’re out of the loop. Out of Ning’s viral loop, that is. The service operates on the exponential principle that anyone who starts a social network will invite friends, family, and associates who, in turn, will bring others on board. In fact, Ning is doubly viral: Some newcomers will also create their own communities.

“We’re not doing any advertising,” says Ning CEO Gina Bianchini, a former investment banker who cofounded the service with Marc Andreessen, one of the creators of the Mosaic browser and cofounder of Netscape. “It’s all being generated virally, which also has the benefit of being – to us – [a way to focus on] product development and R&D, not a big advertising budget.”

Ning’s business plan is mostly based on selling targeted ads to the various niches on its platform. (For $20 per month, individuals can host their own ads.) If there’s a vulnerability it’s this: Some networks are tiny and others are virtual ghost towns. The start-up is leery about releasing data about total numbers of users, but says its largest 250 networks represent around 40 percent of its page views and that 70 percent of its networks have been used in the past 30 days. While Ning’s growth rate is impressive – close to 2,000 new networks per day – it will take more than e-mail invites from each fresh site to attain critical-mass migration.

“Just like a master-plan community of a development of houses, you can build it, but that doesn’t necessarily mean it’s a neighborhood,” says Ben McConnell, coauthor of “Citizen Marketers.” “Growing a community is a big investment of time. The care and nurturing of welcoming people, trying to make them feel welcome, making it easy for them to connect with other people – and then the ongoing challenge of interesting content as a springboard for conversation.”

Mr. McConnell, a customer-retention expert who has a large “Society for Word of Mouth” community on Ning, cites his book’s “One Percent Rule”: Most communities rely on 1 percent of its members to create content. If there isn’t fresh activity to encourage frequent repeat visits, the long tail will tail off.

For now, Ning’s relative ease of use has put its “build your own” platform ahead of competitors such as KickApps, Crowdvine, and GoingOn. But it doesn’t permit users to migrate their networks off its platform. That inhibits Ning’s growth, claims Marc Canter, a leading advocate for an “OpenSocial” Web, and CEO of Broadband Mechanics, a quasi-competitor that custom builds social networks for companies.

“It’s a two-way street,” says Mr. Canter. “If I would set up the wires inside my network to allow a Ning network to move into my world, believe me, I would reciprocate and set up wires from my world to allow people to move to their world.”

Mostly, though, regular Ning users seem to have embraced its relative freedom. “It’s a great business,” enthuses Rubin, the multi-user. “It’s Yahoo Groups on rich media. You can do a lot of this stuff in other places, but they tie it all up in a nice ribbon and make it very easy to do.”