I am working at a company that is tracking vehicles using GNSS antennas. When designing the vehicle dynamics model for the Kalman Filters, I found it useful to have a graphical representation (including error ellipses, velocity vectors etc). Turns out that pygame was a great fit for that type of visualization.
Fast forward to two days ago, when I was idly watching George Hotz design a monocular visual SLAM prototype in 11h. Much to my surprise, one of the first things he fires up is pygame for visualization [1]!