BRL-CAD is a powerful constructive solid geometry solid modeling system that includes an interactive geometry editor, ray-tracing support for rendering and geometric analysis, path-tracing for realistic image synthesis, network distributed framebuffer support, and image and signal-processing tools.
BZFlag is a 3D, multiplayer, tank battle zone, capture the flag game that pits players against each other in a networked environment. It runs on Windows 95/98/NT/2000, Linux, MacOS 10.x, Irix, Solaris, and others. An OpenGL accelerator is highly recommended, but it is playable with 3D in software.
Calc is arbitrary precision arithmetic system that uses a C-like language. It's useful as a calculator, an algorithm prototype, and as a mathematical research tool. More importantly, calc provides a machine-independent means of computation. Calc comes with a rich set of builtin mathematical and programmatic functions.
Racket (formerly PLT Scheme) is a programming language suitable for implementation tasks ranging from scripting to application development, including GUIs, Web services, etc. It includes the DrRacket programming environment, a virtual machine with a just-in-time compiler, tools for creating stand-alone executables, the Racket Web server, extensive libraries, documentation for both beginners and experts, and more. It supports the creation of new programming languages through a rich, expressive syntax system. Example languages include Typed Racket, ACL2, FrTime, and Lazy Racket.
Libgda is a (relatively small) database access library. It provides a wrapper like ODBC but with more features for accessing several database engines, a general data model for use with CSV or XML files, a metadata extractor that retrieves information about database objects in a common way, and a SQL console application (like mysql, psql or sqlite3 consoles).
Hoard is a scalable memory allocator (malloc replacement) for multithreaded applications. Hoard can dramatically improve your application's performance on multicore machines. No changes to your source are necessary; just link it in. Hoard scales linearly up to at least 64 processors. Supported platforms include Linux, Solaris, Mac OS X, and Windows.
IRRToolSet is a set of policy analysis tools, written in C++. It's designed to run under UNIX, using Tcl/Tk for graphics. There are tools for generating router configuration files, displaying and checking routes, generating aggregations of networks, etc. This project was formerly known as the Routing Arbiter ToolSet (RAToolset), and was maintained by ISI.
Loki Setup is a graphical installer for Unix applications. It features descriptions of the package to install in XML, a GTK interface that can be dynamically redefined by the user with Glade, raw and ncurses console interfaces, and the automatic generation of uninstall scripts. It has been successfully used on many Linux and UNIX platforms. It includes tools for uninstalling, patching, and recovering installations. It operates independently from any package managers.
Styx is a scanner/parser generator designed to address some shortcomings of the traditional lex/yacc combination. It has unique features like automatic derivation of depth grammar, production of the derivation tree, including it's C interface, preservation of full source information, pretty printing to faciliate source-source translation, and persistence to aid rapid interpreter writing. It also supports reentrancy. Styx works well under several different OSes, including serveral Unixes, DOS, and Windows.