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 mean, REST-ful JSON APIs can be perfectly type-safe, if their developers actually take care to make them that way. And the self-descriptive nature of JSON is arguably a benefit in really large public-facing APIs. But yeah, gRPC forces a certain amount of type-safety and version control, and gRPC with protobuf is SUCH a pleasure to work with.
Give it time, though, it’s definitely gaining traction.