Data Design Language
Creating live interfaces through direct manipulation of JSON.
Given some JSON, this app will provide you with an interface to describe how you want each entry styled, allowing you to gradually create a more complicated design.
I recommend watching this video to understand it, once you get the general idea, feel free to speed it up to see the whole thing come together. In the video, I create an airbnb-ish app.
See the discussion on Twitter.
(note to self, post screenshot of starting and ending states)
A related idea is my keyboard driven HTML editor: