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.
I’m under the impression that there’s two reasons we don’t have it in chromium yet:
Google already wrote the wuffs language which is specifically designed to handle formats in a fast and safe way but it looks like it only has one dedicated maintainer which means it’s still stuck on a bus factor of 1.
Honestly, Google or Microsoft should just make a team to work on a jpg-xl library in wuffs while adobe should make a team to work on a jpg-xl library in rust/zig.
That way everyone will be happy, we will have two solid implementations, and they’ll both be made focussing on their own features/extensions first so we’ll all have a choice among libraries for different needs (e.g. browser lib focusing on fast decode, creative suite lib for optimised encode).