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.
Hormiga is a language designed to be simple and powerful, allowing users without software programming knowledge to make the programs needed to automate the calculations of everyday problems. Generally, it is necessary only for the users to be aware of the problem they want to solve. The language allows programmers to focus on the problem and not to worry about the interactive interface with the user. The programmer will have to state the instructions to solve a problem, in the same way they would do manually. The steps may depend one upon the other. Like most languages, Hormiga has support for functions and the possibility of creating libraries of commonly used code. Unlike most languages, Hormiga automatically and dynamically creates the graphical user interface (GUI) for programs, has support for calculating definite integrals in multiple dimensions, and incorporates a new concept called Step, similar to a procedure of Pascal, but allowing you to state dependences between them.
Multiple Eyepairs Only is a project to define a file format and to provide tools to use cryptography for things like four-eyes principles. The key idea is this: if information should only be accessible to a group of people together, with the additional possibility to have some redundancy in participants, then MEO is for you.
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.