Digital culture is famous for its democratic principles, and social networking sites such as Friendster, Tickle and Tribe.net are no exception: Anyone can join. But surplus doesn't have nearly the lure of scarcity. At sites like Google's new Orkut.com, the open-door policy is replaced by a velvet-rope approach: Only those who have been invited can join. Supposedly, Orkut will provide higher-quality contacts, screening out the e-rabble that clogs up many online communities. But exclusivity is certainly part of the appeal. "There are lots of old-style country clubs that operate in exactly the same way," says psychologist Chip Heath, a professor at Stanford University's Graduate School of Business.

Will the resulting social network really offer a better way to make contacts? Probably not as much as site creators hope. "An important part of real networking is vouching for somebody who is introduced," explains Heath. "By automatizing that process, you make it less effective." While the sites may speed up connections, the ease of adding "friends" to your online circle makes the quality of those links dubious. The genre is also rife with exploitation and fraud. Some Friendster members claim tens of thousands of "friends"; others devise fake profiles like "Pure Evil." Invitations to join Orkut are already being auctioned on eBay. "All this suggests it's a game people are playing," says Columbia University sociologist Duncan Watts, author of Six Degrees: The Science of a Connected Age.

Orkut advertises itself as "an organically growing network of trusted friends," but exclusivity in online networks never lasts long, says Watts. After all, a key premise behind social networking is that everybody is connected. So Watts suggests the invitation-only model might actually serve a different purpose: destigmatizing online dating. "You can say to other people, 'I didn't join at first, but after people invited me, I said, "What the hell." ' You're offering people a rationalization to do something they would be embarrassed to do."