PythonCard is a GUI construction kit for building cross-platform desktop applications on Windows, Mac OS X, and Linux, using the Python language. The PythonCard motto is "Simple things should be simple and complex things should be possible.

TalkSoup is a fully configurable graphical IRC client for both GNUstep and Mac OS X.

Netclasses is an asynchronous networking library that works with GNUstep and Mac OS X. Out of the box, netclasses gives a nice, asynchronous, and object-oriented interface for IRC, line- based, and raw TCP/IP connections.

Audacity project is a free, easy-to-use audio editor and recorder for Windows, Mac OS X, GNU/Linux, and other operating systems. You can use Audacity to: · Record live audio.

EiffelStudio is the complete Eiffel development platform for Linux/Unix/Windows/Mac OS X. EiffelStudio is a complete development environment for the Eiffel programming language.

RubyScript2Exe transforms your Ruby script into a standalone, compressed Windows, Linux or Mac OS X (Darwin) executable. You can look at it as a "compiler".

AllInOneRuby creates a compressed executable for Windows, Linux or Mac OS X (Darwin) that includes both the Ruby interpreter and the runtime libraries. Why?

PDL::Graphics::AquaTerm is a Perl module that provides access to the AquaTerm Mac OS-X graphics terminal.

JACK is a low-latency audio server, written for POSIX conformant operating systems such as GNU/Linux and Apples OS X.

Mac-on-Linux (MOL) is a virtual machine which runs Mac OS (inlucluding Mac OS X) on top of Linux/ppc.. Mac-on-Linux is a Linux/PPC program that virtualises MacOS or MacOSX in Linux.

QtOIDUA is a graphical user interface for OIDUA for Linux and Mac OS X written in C++ using Qt. It is completely free and open source, and is licensed under the GNU GPL.

ChessX is a free Open Source Chess Database for Linux, Windows, and Mac OS X. The project uses Qt library to create modern, portable graphical interface. Current development is aimed at providing full featured PGN database.

syncpasswd is an Expect script that synchronizes passwords via SSH on multiple platforms (Linux/BSD, OS X, and Solaris). It takes hostnames as a list of arguments and changes the specified user passwords on those hosts.

iLeech is a Mac OS X application that will connect to an iTunes 4.0. Introduced in iTunes v4.0 is the ability to share your playlist with other iTunes users.

YamiPod is a freeware application to efficiently manage your iPod under Mac OS X, Windows and Linux. YamiPod can be run directly from your iPod and needs no installation.

The GNU-Darwin Distribution is an amalgamation of the Darwin and GNU operating systems and a large collection of free software compatible with Darwin and Mac OS X.

RocksnDiamonds is an arcade style game for Linux, Windows, Mac OS X and DOS in the tradition of: "Boulder Dash" (C 64) "Emerald Mine" (Amiga) "Supaplex" (Amiga/PC) "Sokoban" (PC).

LightBlue is a cross-platform Python Bluetooth API. It is available for Mac OS X, GNU/Linux and Nokias Python for Series 60 platform for mobile phones..

GPL Arcade Volleyball is an SDL remake of the old dos game Arcade Volleyball for several platforms (currently Linux, Windows, BeOS and Mac OS X are supported).

Oolite project is a space sim game, written for Mac OS X in Objective C using Cocoa and OpenGL. It was written as my response to the withdrawal of Elite - The New Kind from the internet.