GvR, or Guido van Robot, is a minimalistic programming language that provides just enough syntax to help students learn the concepts of sequencing, conditional branching, looping, and procedural abstraction.
FrAid is a programming language that is appropriate for mathematical computations, visualization, batch processing, and more; features a standalone application.
KLogo Turtle is a Logo language interpretation project for KDE desktops that is useful for teaching geometry and computer programming concepts; supports English, Portuguese, Italian, German, and French.
Groups, Algorithms, and Programming (GAP) is a project for computational discrete algebra with particular emphasis on computational group theory and related areas. I
EGachine is an openly developed project focused on 2D multi-player LAN games; based upon a simple extensible JavaScript shell (EJS) and different modules providing functionality required for programming games.
Code-Forge is an advanced integrated development environment (IDE) that provides full project management and complete edit/compile/debug cycle support for over 30 programming languages.
Beaver is an openly developed editor, for Linux and other Unices (and even Windows); a text editor that is intended to be light-weight, but full of useful features for programming.