Secure scuttlebutt is a totally decentralized append-only "blockchain" with a single writer, that is replicated by various peers who want to get the latest posts. Their mantra is "no global singletons".

https://scuttlebot.io/

Scuttlebutt is very good, but it would be cool to generalize it to the multiple-writers situation. Then we could have one standard for decentralized data streams and even currency tokens, without global networks:

https://github.com/Qbix/architecture/wiki/Internet-2.0