7-Zip
7-Zip is a free file archive manager that supports many different formats, including ZIP and RAR.

Adium
A great Instant Messaging application for OSX that supports many different IM networks and protocols.

Amarok
Amarok is a music player for Linux with an intuitive interface, and many impressive features.

Audacity
Audacity is a free sound editing and recording application.

AVG Anti-Virus
AVG Anti-Virus Free Edition is an anti-virus application that rivals commercial version such as Norton.

Blender
Blender is a 3D modeling and animation program.

Cyberduck
Extremely simple to use open source FTP and SFTP client for the Mac, which seamlessly integrates with a number of other Mac applications.

Deluge
A lightweight cross-platform BitTorrent application that has plugin support.

FileZilla
FileZilla is a cross-platform FTP client that supports secure file transfer.

Firefox
Firefox is an excellent free browser that provides a much more secure and friendly browsing experience that Microsoft Internet Explorer.

Foxit Reader
Foxit Reader is a lightweight alternative to Adobe's Acrobat PDF reader.

GIMP
GIMP (The GNU Image Manipulation Program) is a free image editor similar to Photoshop. It can be used for things like photo retouching, image composition and image authoring.

Google Earth
Google Earth combines satellite imagery, maps, terrain and buildings onto a 3D globe that you can move around.

Google Pack
A one-stop software package that helps you discover, install, and maintain a wide range of essential PC programs.

Handbrake
Handbrake is a DVD ripping application, allowing you to convert a DVD to a video file.

Inkscape
Inkscape is an open-source vector graphics editor similar to Adobe Illustrator or Corel Draw.

NeoOffice
NeoOffice is a native Mac OSX port of OpenOffice.

NVu
A complete Web Authoring System that rivals programs such as FrontPage and Dreamweaver.

OpenOffice
OpenOffice is a free and full featured alternative to Microsoft's office suite.

Opera
An award winning free Web browser that is a very fast and feature packed.

Paint.NET
A fully featured but easy to use image editing application.

Pidgin
Pidgin, formerly known as Gaim, is a multi-protocol instant messenger client, working with Yahoo IM, AIM, Google talk, MSN and others.

SciTE
A feature packed text editor with many advances features for programmers.

Scribus
Scribus is a Desktop Publishing (DTP) application which can be used to create professional quality documents.

Skype
Skype allows you to make phone calls from your computer - to other skype users for free, and very cheaply to phones and mobiles.

Thunderbird
Simple and lightweight email and news application.

Transmission
A very lightweight and easy to use BitTorrent application.

VLC media player
VLC is a media player that supports many different audio and video file formats.

WinSCP
A simple FTP and SFTP client for Windows.

µTorrent
µTorrent is the most popular BitTorrent P2P application for windows.