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.
A degree Celsius is not coarse and does not require decimals in weather reports, and I suspect only a person who has never lived in a Celsius-using country could make such silly claims.