Five Hundred is a card game for four players similar to Euchre or Bridge, especially popular in Australia and New Zealand. The wikipedia page has a comprehensive description of gameplay. This version is implemented in C++/Qt. It incorporates graphics from the svg-cards project. Computer players are scriptable in Lua.
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.
SourceNote is a program for taking notes. It lets you add text, pictures, and your own drawings, all of which are packed into different boxes which you can move around, making organization easier. The interaction is optimized so that you can switch easily between your opened tabs, as in a browser.
comedi2py feeds data from a data acquisition board into Python by using call-back functions. The goal was to make this as easy as possible, hiding all the complexity of the asynchronous acquisition in comedi2py and providing the Python program simply with an array of the sampled data at a given sampling rate. The program has been tested with the USB-DUX boards, but should also run with any other COMEDI supported data acquisition board.
parsical is a Shehensai or parsi calendar application. It's useful for prayers, birthdays, weddings, navjotes, jashans, and other events. It features sunrise calculation based on the computer timezone (as roj begins at sunrise in this calendar), "previous" and "next" month and year buttons, conversion between Gregorian and Shehensai dates, and jumping to the calendar month on a given date or roj.