PySide provides a full set of Qt bindings and automated binding generation tools. The binding generation tools can be useful for creators of Python bindings to any Qt-based library or to any C++ library in general. Although based on a different technical approach, PySide will initially be API-compatible with existing Python bindings for Qt.
QMentat helps you practice mental arithmetic. It uses arbitrary-length fixed point arithmetic, and can handle any size numbers, only limited by the size of your screen (and in the case of division with an integer result, the speed at which the number can be factored). It is also quite configurable, allowing you to tailor the questions to your needs.
QSapecNG (Symbolic Analysis Program for Electric Circuits (New Generation)) is a Qt-based program for symbolic analysis of linear analog circuits. It consists of two independent parts, the SapecNG framework engine and the QSapecNG GUI. It was based on SapWin. Users can draw, solve, analyse, and manage analog circuits.
SecureCam is a video surveillance system with a nice GUI. It supports multiple camera and video file inputs. It detects motion in input video using fast algorithms. Alarm notification is provided by email, alarm sound, and video recording. Currently, only a Windows installer is provided, but the source can be compiled on Linux.