I haven't come across a way to send and receive dynamically-typed data. For example, I have some tables in my database with columns that store JSON data. When serializing one of these columns, I don't want to send the value as a string, but rather as an embedded JSON object.
I'm thinking maybe we invent an attribute like [SerializeAsRawJson]. If it is present on a string property, the formatter will embed it as a raw JSON object instead of as a string.