Yonks ago (about 2004) I became very excited about the concept of 'Federating' servers of various kinds. None of them really gained enough inertia, i.e. enough users to actually take off. Others had the 'wrong' (read 'non-free') style of license and it was the wild west as far as protocols were concerned.
 
Personally, I think that some of the problem was there simply weren't enough social internet users out there. Just geeks on IRC and some forums. Mind you facebook was brand-new in 2004 and twitter didn't show up until 2006. Both of these things are now popular. Each are controlled by a single corporation which a) doesn't give a fig for your privacy and (b) is constantly pissing off its users by changing things trying to maximize profit. Or so I've read. I don't  use either of them myself.
 
So to 'fix' the problems with the birdsite a guy in France simply re-wrote it. He made it more like what he liked about twitter originally in look and feel, he upped the privacy, he upped the length of messages to 500char, and some other stuff, but most importantly, he made it open source and federated: anyone can run their own server of Mastodon. Each server can communicate with every other server. It kind of just took off in May. Look at all these servers! "There are currently 1598 instances being tracked, with a total of 651237 users." https://instances.mastodon.xyz/list Wow! Some are completely private, some have only 1-2 users and some have over 100,000 users, but they are all federated together and users on one instance (server) can contact and follow any other user on some other instance. My 'home' instance happens to be in Oz, because it was near the top of the list the day I signed up, but I still follow people in e.g. Argentina (I want to learn to write and read Spanish), France, South Africa and even Japan. I get exposed to a lot of art, tech and ideas. Also, some dreck, but there are convenient buttons to block and mute people easily. And no one can control it or turn it off! Plus, it is compatible with other GNU attempts that didn't take off, they are now a part of The Federation too. My goodness! It's like Star Trek FFS! :-)
 
Another thing (with an unfortunate name) is Matrix. The word is just too darn common! http://matrix.org/ Ah! What have we here? In my words, it's kind of like internet relay chat (IRC), but federated AND encrypted with public and private keys. It can be in-browser, in an app on your phone or from the command line. FAQ: http://matrix.org/docs/guides/faq.html and clients are here http://matrix.org/docs/projects/try-matrix-now.html Oh, also voice and video! Encrypted with no microsoft/cia/skype in the way. I have very high hopes for this taking off too and very soon. I see Mozilla Thunderbird is planning support for Matrix http://matrix.org/docs/projects/client/thunderbird.html
 
I only thought to make this little post, because of https://mastodon.social/@AMID_EVIL and his lovely list! Several projects are new to me and I still have to go through them. Also, I believe Sandstorm should be in the mix as, while it isn't federated, it is very empowering with multiple instances, privacy centered and very open and secure.
 
 
//mastodon.social/@AMID_EVIL"> Dmitry @AMID_EVIL

P2P tools for developing decetralized services:

blockstack.org/
Blockstack is a new decentralized internet where users own their data and apps run locally. A browser portal is all that’s needed to get started.

ipfs.io/
A peer-to-peer hypermedia protocol
to make the web faster, safer, and more open.

matrix.org/
An open network for secure, decentralized communication.

lbry.io/
LBRY is a free, open, and community-run digital marketplace.