OSCP is a project that I'm working on that looks and operates similar to the calculator found in Windows. It is completely open source (Hence the name) and is programmed in Visual C++. The current version is 0.0.5.0, therefore early alpha stage. I still have a long while to go, but basic functionality is working for the most part. Don't forget to report bugs!
Source and Application:
http://www.aldude999.tk/Downloads/OSCP.zip
(Application is under Release.)