Since it seems the whole world wants one, NMK asked iStockphoto about what makes for a successful social network, and how others might learn from them.

Founder Bruce Livingstone describes iStockphoto as the first social network that monetised user content. While most user-driven networks, such as YouTube and flickr, offer their content for free, iStockphoto sells its users' photos in return for a share of their sale price. Photos sell from $1, depending on their size and the photographer's popularity, which might sound like small change compared to the prices charged by stock libraries such as the site's parent company (since February 2006) Getty Images. Nonetheless, Livingstone says, there are a significant number of users making tens of thousands of dollars a year from their photographs and some are making between two and three hundred thousand dollars a year from the accumulated value of these micropayments.

The site has 1.7mn members, with around 38,000 contributing photographs and other items to the site. It has branched into video fairly recently and has attracted around 1000 video artists to upload and sell content.

So what has been its secret? Perhaps that money came relatively late into the equation. "The company was built on passion, not dollars," says Livingstone. It was launched as a free hosting site for photographers, and the focus of the site has been on helping people showcase their work and to produce better photography. The strong community means that not all rewards are monetary, with status-based rewards as well as money. "There's a huge amount of educational material on the site," says Livingstone, which also boasts very active discussion forums as well as contributed feature articles passing on information and advice. The community also produces a number of live events, which work as photoshoots with the site organising models, lighting and costumes, and photographers turning up to learn more about working in a professional environment.

Will other brands creating social networks succeed? Livingstone isn't sure that they will, at least, not in the same way. "It's often like putting on a T-shirt that's two sizes too small," he says. And the topic of the community makes a considerable difference. Livingstone can't see how 'institution-based' networks that are based on what school or university you go to, are likely to work long term: "Classmates are not a community. It's disjointed." He can imagine that networks around a topic that people are genuinely passionate about, such as mobile phones, could achieve some traction, though.

In order to work as a marketplace, iStockphoto tries to maintain high professional standards when it comes to the photos it agrees to put on sale. The company employs 82 image inspectors - independent contractors in countries across the world - who look at every contributed image before it is added to the site. Almost 40 per cent of images are turned down - normally on the grounds of quality, and the moderators try to provide advise about how better lighting or composition might have made the image better. Subject matter can also result in exclusion, though this only applies to a small minority of cases. While they allow 'artistic' images, in the same way as other photo libraries, nothing pornographic is allowed on the site. Vice President Kelly Thompson explains that moderation is one means by which they maintain their position in the market: "We'll put our collection up against any place on the planet when it comes to quality. We also sell more images than any other supplier."