RetroShare is probably the only one more or less "finished" right now. There is also a similar one from FSF called GnuNet, and a very Twitter-like alternative called Twister, but they are both pretty alpha. If you also want a Skype alternative there's Jitsi, and a new one called Tox, but I haven't looked much into it. I think it's also pretty alpha.

http://retroshare.sourceforge.net/

https://gnunet.org/

http://twister.net.co/

https://jitsi.org/

http://tox.im/en

For mobile you can take your pick from these:

https://missingm.co/2014/02/fighting-dishfire-the-state-of-m...

check out social engine ... pretty good one http://socialengine.com