At drchrono (#1 iPad EHR on the Market, YC W'2011) we are building a very open API that has an open door policy to our customers and other digital health startups.

If anyone is working in the digital healthcare space we'd love to work with you. You can get access to and build on our JSON API in 1-2 days. Sign up here: https://drchrono.com/api

Here is a youtube video we shot with a startup that built on our API: https://www.youtube.com/watch?v=HBCIzuXEH44