Coupled Oscillator Simulator
The original version of the software that formed a basis for my PhD was written in C++ using OpenGL as a display driver.
The software executed high performance mathematical simulations on a variety of Operating Systems (primarily Linux and Windows) and displayed the current status of the simulation to the screen using the Open GL libraries.
Later versions of the source code where modified to allow for changes to be made to the system in real-time. The software was also written so that the simulations could be exported to an AVI video file so that they could be played back in presentations and seminars without requiring the software itself to be deployed.