Open Source

Blender - the free open source 3D content creation suite.

Blender is the free open source 3D content creation suite, available for all major operating systems under the GNU General Public License.
GIMP - The GNU Image Manipulation Program.

The GNU Image Manipulation Program, for X Windows systems. Official site, including download area, documentation, FAQs, and a plugin registry.
GNOME: The Free Software Desktop Project

GNU Object Model Environment: Building a full, user-friendly desktop for Unix operating systems, based entirely on free software.
Google Code

Google's official developer site. Featuring APIs, developer tools and technical resources.
Inkscape - Open Source vector graphics editor.

An Open Source vector graphics editor, with capabilities similar to Illustrator, CorelDraw, or Xara X, using the W3C standard Scalable Vector Graphics (SVG) file format.
PHP: Hypertext Preprocessor

Main site for the free server-side HTML embedded scripting language.
Project Hosting on Google Code

Project Hosting on Google Code is fast, reliable, and easy open source hosting service.
Python Programming Language - Official Website

Official site for Python, a dynamic object-oriented programming language that can be used for many kinds of software development on a variety of platforms. Includes downloads, documentation, and information for beginners.
SourceForge.net

SourceForge.net. Fast, secure and free downloads from the largest Open Source applications and software directory.
The Apache Software Foundation

The Apache Software Foundation provides support for the Apache community of open-source software projects.
The GNU Operating System

Since 1983, developing the free Unix style operating system GNU, so that computer users can have the freedom to share and improve the software they use.