There are a couple I have in mind. Like many techies, I am a huge fan of RSS for content distribution and XMPP for federated communication.
The really niche one I like is S-expressions as a data format and configuration in place of json, yaml, toml, etc.
I am a big fan of Plaintext formats, although I wish markdown had a few more features like tables.
Okay here it goes!
Tenfingers sharing protocol & python implementation (your python needs cryptodomex, or use the frozen executables).
http://tenfingers.org
You share theirs, they share yours (all encrypted)! So no benevolent nodes or crypto and it’s 100% decentralised.
I’m working on a better documentation on how to set it up (just forward a port and run setup basically).