Jmol is a Free, Open Source molecule viewer and editor. It is a collaboratively developed visualization and measurement tool for chemical scientists. Jmol is an active project, and there are new features being added to it on a daily basis. Users are encouraged to modify it to fit their needs and to contribute their changes to the project.
AccuRev is a fast, powerful, and easy-to-use Software Configuration Management (SCM) tool with integrated issue tracking based on "Streams" that more efficiently manages complex parallel and global development. Streams are a combination and superset of branches and labels that are first class objects instead of being file-by-file attributes. AccuRev records all merges and patches, so you never have to re-merge the same code. It supports file and directory renaming and merging, follows a client/server model, and is transaction-based. It includes an integrated graphical 3-way diff and merge tool. AccuRev provides an Open API (and SDK) to integrate with any third-party development tool (IBM/Rational ClearQuest, Serena TeamTrack, and more out of the box). It also integrates with Eclipse, the MS SCC API (MS Visual Studio), Sun Java Studio, any diff/merge tool with a command line interface, and more.
Yacas is a general purpose, easy to use Computer Algebra System (a CAS is a program that can be used to do symbolic manipulation of mathematical expressions). It is built on top of its own programming language designed for this purpose, in which new algorithms can easily be implemented. In addition, it comes with extensive documentation on the functionality implemented and methods used to implement them.
Xplanet was inspired by Xearth, which renders an image of the earth into the X root window. All of the major planets and most satellites can be drawn, similar to JPL's Solar System Simulator. A number of different map projections are also supported, including azimuthal, Mercator, Mollweide, orthographic, and rectangular.
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.
tn5250 is a 5250 terminal emulator, used for connecting to IBM's AS/400 (now known as eServer iSeries) midrange computers. tn5250 implements TN5250E, which means it is capable of device name selection, and printer sessions. The emulator supports color, 132 column mode, and most other features found in 5250 terminals and Client Access' 5250 emulator. While tn5250 is text-based application, a script is included to run it in an xterm properly. If you don't know what an AS/400 is, this program will probably not be of much use to you.