Ding is a dictionary lookup program for the X Window system on Linux/Unix. It comes with a German-English Dictionary with about 253,000 entries. It is based on Tk version >= 8.3 and uses the agrep or egrep tools for searching. In addition ding can also search in English dictionaries using dict(1) and check spelling using ispell(1). It has many configuration options, such as search preferences, interface language (English or German), and colors. It has history and help functions and comes with useful key and mouse bindings for quick and easy lookups.
Dr. Geo is an interactive geometry program that is distributed as a universal portable application. It allows one to create a geometric sketch and manipulate it according to its constraints. It is usable at home or at school, in primary or secondary education. It is simple and effective with extended features including scripting and programming.
GCompris is an educational software suite with numerous activities for children aged 2 to 10. Some of the activities are game-orientated, but nonetheless still educational. These include computer discovery (keyboard, mouse, different mouse gestures), algebra (table memory, enumeration, double entry table, mirror image), science (the canal lock, the water cycle, the submarine, electric simulation), geography (place the country on the map), games (chess, memory, connect 4, oware, sudoku), reading practice, and others (learn to tell time, puzzles of famous paintings, vector drawing, cartoon making, etc.). It currently offers in excess of 100 activities, and more are being developed.