Professionally, I split my time between C and C# about 50/50. Our main application is written in C, and since I joined the team I have Integrated an ever growing C# module into the solution in a way that we can execute managed code in process with our C app.

I've also introduced my company to WPF, and have lately been spending a considerable amount of time setting up the infrastructure such that it can be used from our C app. The magic language that allows us to run C# code from the C app is C++/CLI, where it is a mid-layer between managed and unmanaged code.

In addition, I've developed .NET add-ins for AutoCAD, Inventor and Excel, such that everything is integrated with our main application.