Thinking about the DMGI Maxim of "HTTP RESTful API's (using JSON) will serve all data and core transactions - the same api's will serve internal application requirements and external partners" I've been looking for a tiny C# web server to add to our production 'robots'. Each robot would then have some standard api objects like logs, jobs, and report counts that could be queried on-the-fly.
Internally, we use a lot of XML. In my hobby project I am now moving towards 'everything in GeoJson' whenever possible. This works nicely because geo things can be hooked into maps at any time really easily.
Project Katana http://www.asp.net/aspnet/overview/owin-and-katana/an-overview-of-project-katana looks like a good candidate.
https://github.com/unosquare/embedio might have worked, but I would prefer a more mainstream development.
and some people have implemented simple REST http://weblogs.asp.net/fredriknormen/creating-a-simple-rest-like-service-with-owin-open-web-server-interface
There doesn't appear to be native JSON parsing, but Json.NET looks viable http://json.codeplex.com/