Our primary development language is C# on the .NET Framework for standard application development.
If we need to implement something which is lower level, we generally implement it in C or C++, depending on the requirements, of course also as managed C++ in .NET.
We have in the past developed for MFC and many other windowing libraries under DOS using C. We have also done embedded development in C and 808x assembler.
We have also done substantial development in many forms of BASIC and Visual Basic for .NET, Visual Basic for Applications and Windows Scripting.
Other languages we have used include Smalltalk and Delphi.