Social networks profilerate – where do I start?

Facebook, Linked In, Xing, Ecademy… I’m starting to get swamped by different social networking systems. What, if any, is the point of adding people as friends / contacts in more than one of these systems? Plus for Linked In, Xing and Ecademy you have to even pay cash to get the full functions. Ecademy is €16.45 a month for its ‘proactive networking’ and LinkedIn is $19.95 a month for a Business account – that’s more than I pay to host all my own websites each month, and that allows me to create my own Global Microbrand via my blog. Facebook is at least free for all its functions, so for that reason it will carry on being my network of choice.

Beyond that I could host my own social network on my own server with ELGG, or on someone else’s server with Ning or ONEsite. I could even start to network things together… Would there be any point of doing so though? Something separate for a political site perhaps?

However one thing I won’t be doing is to join StudiVZ, the German equivalent of Facebook. They need a date of birth in order to signup, and on any Mac browser (Firefox, Safari, Opera) 2 parts of the ‘Geburtstag‘ fields are greyed out and I can’t enter a date – even with popup blocker off, and all javascript etc. enabled. Bit of an oversight when you consider Apple’s growing market share.