JSON Table Schema
dataprotocols.org
dataprotocols.org
These are specific use-cases, and in no way encumber other uses of JSON.
Personally, I'd love to see a universal format that all database vendors use, instead of vendor-specific DDL.
On the other hand, such standarizations tend to become overengineered monstrosities that no one wants to use in the real world. An example of this seems to be JSON HAL which I decided is too complex to implement in an API.