LONDON, England (CNN) -- Every day, millions of people use social networking sites like MySpace and Facebook to stay in touch with friends, make business contacts and procrastinate at work.
Aka aki is a social network on your cell phone that lets you know when you pass by other members.
But social networking is still in its infancy -- its adulthood promises to be far more exciting, according to experts like Caterina Fake.
Fake has been involved in blogging and online communities since the 1990s. She co-founded pioneering photo-sharing site Flickr in 2004, and sold the site to Yahoo! in a multi-million dollar deal in 2005.
More than just a place to store your photos online, Flickr always encouraged sharing and collaboration among its users.
Key to its success was the way it let users browse other people's images, adding comments and forming groups based on shared interests or friends -- allowing its users form a social network where they could interact with each other.
Fake told CNN that, far from being a fad, social networking is here to stay. "Online sociality is really the nature of the Internet. The first thing that made people love the Internet was instant messaging, email and all the communication tools.
"I've read that 25% of all Internet traffic is social networking, and the reason is that people have an incredibly powerful desire to communicate with each other, and that will never go away," she said.
But Fake thinks the way we use social networks is starting to evolve. "I think there's a kind of over-connecting happening. People are starting to realize that having so many contacts and keeping on top of so many people's lives is actually quite a lot of work.
"I think there's a trend away from 'promiscuous friending' to a more selective social group," she said.
Fake thinks that the future of social networking is not in rigid networks of friends, but in more subtle social collaboration. "I think that in many ways the 'explicit' social networks are less powerful than the less-social networks.
"One of the reasons that Flickr works is that the photos on there are public. Somebody in Tokyo will have uploaded a photo of the hotel you want to visit; this isn't somebody you know, but it's a social system in that other people are contributing to it, they are connected to other people, and those people are adding meta data to their photos," she says.
"There's a sort of wisdom of crowds and collective knowledge that's actually the product of sociality, but isn't directly related to that person being connected to you. So the social systems are much more interesting in many ways, and will be in the future."
If the future of social networking is in collaboration, it's also in real-world sociability.
Perhaps with this in mind, German company aka-aki is on a mission to get social networkers away from their PCs and onto the streets.
You can download its service to your cell phone for free and if your phone has Bluetooth it will vibrate when another aka-aki member comes within 20 meters of you. You can then view that person's profile and, if you like what you see, message them, or perhaps even risk a real-life conversation. Would you want to see the profiles of people you pass in the street?
Launched in April this year, aka-aki now has nearly 13,000 users. But where other social networks aim to increase their membership as rapidly as possible, for aka-aki it's essential that membership is initially concentrated in one area, so that members are likely to run into each other.
This kind of mobile social networking could revolutionize your social life. If you're at a night club and you want to know who's around, just check your cell phone.
If you're at a party you can scan for someone with the same interests as you, or just check out who's single. Of course, you can set up filters, so that you are only detected by your friends, or friends of friends, or people who share your passion for Bolivian folk music -- or you can simply turn off the Bluetooth feature altogether.
There's even a "diary of encounters" feature on the web site that allows you to review all the Bluetooth contacts you've received that day, which aka-aki co-founder Roman Hänsler says has turned out to have a surprising application.
"We experienced that when we went to an industry event, and there were a lot of people using aka-aki, you don't need business cards anymore, because afterwards you can just see who you met and get their information. I call it the end of the business card," he told CNN.
But aka-aki is working on something far more interesting than just replacing the business card.
Hänsler told CNN that although the service will remain free for users, ultimately aka-aki intends to sell profile space to commercial ventures. "A shop or brand can have a profile at aka-aki and you could 'meet' a shop, or a shop could tell who is passing it every morning and maybe offer that person a voucher for something, or tell them when they have special offers," he said.
Aka-aki is currently focused on Bluetooth technology, because it's so widespread in cell phones, but the GPS technology in Apple's iPhone is even more exciting, because of its ability to pinpoint the position of its users outdoors, with the iPhone's wi-fi detection performing a similar function indoors.
Google's newly launched Android cell phone platform has similar potential and social networking applications are already being developed for it. Google's Android Developer Challenge, announced last year, awarded $275,000 to each of the 10 best applications being developed for Android.
Many of the winning applications had some kind of social networking feature, including Life360, a location-based system that, among other things, allows users to form social networks with others in their neighborhood.
Another developer came up with Commandro, a social networking application that uses GPS to let you know where your friends are. You could use it to spot that a friend is a couple of blocks away and arrange an impromptu meeting. It also lets you set up alerts -- for example when one of your of friends is within a certain distance of a given location -- ideal if you're trying to avoid that friend you owe $20.
As social networking becomes more widespread, many see openness as the big trend that will emerge over the next few years.
Currently, the biggest social networking sites exist as "walled gardens." The profile you set up on, say, Facebook, is only accessible to Facebook users. That's fine as long as all your friends use Facebook, but what if they have a MySpace profile instead? And what if you have a profile on one network, but you also want to join another?
Joining a new network means setting up a new profile from scratch and having to trawl that network for people who might already be your friends on another network. It all seems a bit ... 2004.
Many people, including Hänsler, think the "walled gardens" will have to go, so that one profile and its associated "social graph" (network of contacts) can be transferred between different social networks.
Hansler says aka-aki is open to co-operation with other social networks, but currently most networks are too intent on keeping hold of their own users. Essentially, there's no incentive for the biggest social networks to have this kind of openness, because it would make it easier for their users to transfer to other networks, but Hansler says this will change.
Fake, however, has her doubts about the need for this kind of openness, saying that people want to have different profiles tailored to different networks. "I think you have one kind of personality on Facebook and another personality on LinkedIn, and having them separate is an advantage," she says.
"People have been talking about these über social networks since time immemorial but they've yet to gain any traction.
"I think that's because people want to move from one group to another and maintain different kinds of relationships with different people."