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.
Steel Bank Common Lisp is a development environment for Common Lisp, with excellent support for the ANSI standard: garbage collection, lexical closures, powerful macros, strong dynamic typing, incremental compilation, and the famous Common Lisp Object System (multimethods and all). It also includes many extensions, such as native threads, socket support, a statistical profiler, programmable streams, and more. These are all available through an integrated, interactive native compiler which feels like an interpreter. SBCL is unique in being a multiplatform native compiler which bootstraps itself completely from source, using a C compiler and any other ANSI Common Lisp implementation.
Moosic is a music player that focuses on easy playlist management. It consists of a server process that maintains a queue of music files to play and a client program which sends commands to the server. The server continually runs through its playlist, popping items off the top of the list and playing each with an external program. The client is a simple command-line utility which allows you to perform powerful operations upon the server's queue, including the addition of whole directory trees, automatic shuffling, and item removal according to regular expressions. The server comes configured to play MP3, Ogg, MIDI, MOD, and WAV files.
BitTorrent is a tool for copying files from one machine to another. FTP punishes sites for being popular. Since all uploading is done from one place, a popular site needs big iron and big bandwidth. With BitTorrent, clients automatically mirror files they download, making the publisher's burden almost nothing.
Java Development Environment for Emacs (JDEE) is an Emacs-based integrated development environment (IDE) for developing Java applications and applets. Features include multiple code browsers, a JPDA-based debugger, method and field completion, template-based and procedure-based code generation, Java source code interpreter, context-sensitive help, and more.
Glypha III is a Mac OS X port of the classic arcade game in which you are placed inside an Egyptian temple and forced to do battle with Sphinxes in order to gain the honour of a place in the High Scores. The game is based on Joust and features sound and animated graphics from the original Mac version.
mfw allows multiple firewall configurations to be managed from the commandline on Mac OS X. Multiple firewall modes (and easy means of selecting between them) are useful on laptops, where one may want a default paranoid firewall, a mode for network scanning with nmap, modes for various networked games, or to run a software Network Address Translation (NAT) wireless base station.