In the course of writing Universe2 I had need of a control for setting the date in Imperial format. I wanted something that looked like the standard MonthCalendar control, and here it is: ImperialCalendar.
The download is a ZIP of the DLL. It was written in C#.NET 2.0 and requires the .NET 2.0 Framework be installed. Simply drop the DLL into the bin directory of whatever project you are working on and add a reference to it in your toolbox. The namespace is Trisen.Traveller.Controls and it contains the ImperialCalendar control (which should be fairly self explanatory).
The optional Holiday dates are in line with T5.