At this moment, there are atleast 100 ACTIVE Social networking sites....and atleast one social networking site is booting up and will release a beta version at any moment. Can't believe? Have a look at a list of them at Wiki here. Now this list is not up-to-date and does not have local and upcoming sites yet, for example Minglebox from India is absent from the list. So you get an idea, how many sites might be there out and running in betas.
If you have been wandering on the web for a while, you must be wondering the same, Which one shall I use? Or shall I use more than one of them?
And unfortunately there is no quick and definitive answer. Every social networking site, barring a few, is a narrowly focussed, often times, single feature website or narrowly focused on a certain group of people. Now without any hesitation, every body needs more than just one feature. And every body want to network with more than one group of people belong to more than one nation. Many of us love music, die to shop, crave to eat out, travel mad ..... !!! You got my point.
As per my knowledge not all sites support APIs to integrate or interwork with other sites. So mashup is quite difficult if not impossible. There were some mashups (like pageflakes) with widget support to limited features of some of these sites. But not quite there yet.
Is there a way out?