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.
That looks like an interesting diagram, but the text in it renders too small to read easily on the screen I’m using, and trying to open it leads to a javascript complaint and a redirect that activates before I can click to allow javascript. If it’s yours, you might want to look in to that.
The table below works, though. Thanks for the link.
Alas it’s not my site (and I think it’s meant to be read on a desktop screen), so I can’t fix it.