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.
GRPC for building APIs instead of REST. Type safety makes life easier
The biggest problems with gRPC are:
Plain HTTP can be type safe. Just publish JSON schema or Typespec files or even use Protobuf.