Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
Most people won't have even heard of it. Diaspora is an up and coming social network which is getting a lot more attention in some circles in the wake of Google+'s 'real names' policy.
Users are climbing on board after being tipped off that there's a network just like Google+, only without having anything to do with Google, where you can be who you want to be, how you want to be, and still retain full ownership of everything you put there.
Currently invite-only and in alpha, preparing to roll out beta, Diaspora is an open-source social network. It's run on free software that anyone with a little bit of coding know-how can get involved in developing. The community involvement in running the site is huge. From spreading the word to community support, it's all open for volunteering.
Unlike Facebook and Google+, company-run businesses which aim to get as much data from you as they possibly can, the guys behind Diaspora take a completely different view: