Social networking sites -- accept you won't be the only one, and start interoperating.
So many social networking sites (LinkedIn, Orkut, Friendster, Tribe, Myspace etc.) seem bent on being islands. But there can't be just one player in this space, not even one player in each niche. But when you join a new one it's like starting all over again. I routinely get invitations to join new social applications, and I just ignore them. It's not worth the effort.
At some point, 2 or more of the medium sized ones should realize that the way to beat #1 is to find a way to join forces. To make it possible on service A to tie to a friend on service B, and to get almost all the benefits you would have if both people were on the same service. Then you can pick a home service, and link to people on their home services.
This is a tall order, especially while protecting highly private information. It is not enough to simply define a file format, like the FOAF format, for transporting data from one service to another. At best that's likely only to get you the intersection of features of all the services using the format, and an aging intersection at that.
How to do this while preserving the business models and uniqueness of the services is challenging. For example, some services want to charge you for distant contacts or certain types of searches of your social network. And what do you do when a FoF involves the first friend being on service B and the FoF being on service C.
Truth is, we all belong to many social networks. They won't all be in one system, ever.
You can't just have routine sharing. This is private information, we don't want spammers or marketers harvesting it.
The interchange format will have to be very dynamic. That means that as soon as one service supports a new feature, it should be possible for the format to start supporting it right away, without a committee having to bless a new standard. That means different people will do the same thing in different ways, and that has to be reconciled nicely in the future, not before we start using it.
Of course, at the same time I remain curious about just what they hope for us to do with these social networks. So far I have mostly seen them as a source of entertainment. Real live-altering experiences are rare. Some are using them for business networking and job hunting. Mailing FoFs didn't really work out, it quickly became more spam than anything. Searching a network (the ideal app for Google's Orkut) has not yet been done well.
Perhaps the right answer is to keep the networks simple and then let the applications build on top of them, independent of how the networks themselves are implemented. This means, however, a way to give an individual application access to your social network and -- this is tricky -- the social networks of your friends. Perhaps what we need is a platform, implemented by many, upon which social applications can then be built by many. However, each one will need to ask for access, which might encourage applications to group together to ask as a group. The platform providers should provide few applications. In effect, even browsing your network is not an application the provider should offer, as that has to travel over many providers.
Once some smaller networks figure this out, the larger ones will have to join or fall. Because I don't want to have to keep joining different networks, but I will join new applications based on my network.