Cactus is a general, modular, parallel environment for solving systems of partial differential equations. The code has been developed over many years by a large international collaboration of numerical relativity and computational science research groups and can be used to provide a portable platform for solving any system of partial differential equations.
e3 is a full-screen, user-friendly text editor with an interface similar to that of either WordStar, Emacs, Pico, Nedit, or vi. It's heavily optimized for size and independent of libc or any other libraries, making it useful for mini-Linux distributions and rescue disks. The assembler version supports Linux, FreeBSD, OpenBSD, NetBSD, Win9x, QNX, Atheos, BeOS, ELKS, and DOS. There is also a separately distributed version written in C which supports some other Unix versions and CygWin. It is also possible to use regular expressions by using child processes like sed. e3 has a built in arithmetic calculator.
GNU Go is free program that plays the ancient board game of Go. Its original concept is based on the article "Programming the Game of Go", Byte, Vol.6 No.4, by J. K. Millen. GNU Go has since evolved into a more sophisticated program. After thousands of games played on the No Name Go Server (NNGS), it is rated around the 8th kyu level.
Gri is an extensible plotting program designed for scientists. It can draw x-y plots, contour plots, and image plots, and has rudimentary programming capabilities. Output is PostScript. Gri is not mouse driven, nor GUI-based; it is a language. Users regard it as an analogue to the LaTeX document formatting language: users gain considerable power, at the price of a moderate learning curve.
Groups, Algorithms, and Programming (GAP) is a system for computational discrete algebra with particular emphasis on computational group theory and related areas. It provides a Pascal-like interpreted language, data types for many algebraic objects, a function library, and large libraries of data.
Gyach is a GTK+-based Yahoo! Chat client which can use your existing Yahoo! logins for chatting in Yahoo! Chat. It supports colors, emotes/aliases, PMs, set status, remote user status display, ignore lists (local, non-Yahoo! based), a regex list of triggers to cause users to be automatically ignored, command-line recall via arrow keys, and tab completion of usernames.
HTTrack is an easy-to-use offline browser utility. It allows you to download a Web site from the Internet to a local directory, building recursively all directories, getting HTML, images, and other files from the server to your computer. HTTrack arranges the original site's relative link-structure. Simply open a page of the mirrored Web site in your browser, and you can browse the site from link to link, as if you were viewing it online. HTTrack can also update an existing mirrored site, and resume interrupted downloads. WebHTTrack is a Web-based GUI for HTTrack.
interpcom is a command interpreter library in C that can be used to build scientific applications. It is very easy to add new commands. The library contains an expression evaluator that can be used to parse the arguments of the commands. It is possible to define "objects" which are arrays of numbers having a name, and structures. It is possible to use threads (several programs running simultaneously).