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.
ArduinoPulseGenerator is a simple program for generating pulse sequences using an Arduino. There is an associated GUI that runs on the local computer, or you can simply connect to the Arduino with a serial console (9600 baud) and send it commands. This code has been tested on the ArduinoMega 2560 (timing accuracy ~ ±200 μs) and Arduino Due (timing accuracy ~ ±35 μs); it may work on other Arduino boards.
Liquid War 6 is an original multiplayer wargame. You have to control an army formed with thousands of pixels that look like liquid, and try and eat your opponent. This is a total rewrite of the (now quite old) Liquid War 5 version. It's still in beta stage, with many imperfections and no network play but it's playable now.
Vocab Builder is a collection of two separate programs. The client is the testing application that uses a drill-style method of building your vocabulary in a foreign language, similar to using flash-cards. The editor allows you to create a new, or modify an existing, database for your own personal use. Since the design of the project allows a user to create their own databases/tests, they can not only focus on the words they want/need to learn, but also are not restricted by availability of choice. No more are you restricted by only the databases available to you. Many language teaching applications only allow you to learn the languages they've supplied you. Most North American-based programs cater to English speaking users and only give you a selection of other languages to choose from. Not only can Vocab Builder use any language combination of Native and Secondary languages but it's also open-ended. You can share your tests with others. You can expand the database of words in any direction you want. Word lists are meant to be broken down into categories like colors, sizes, numbers, etc.