A full featured office software package. The full package - OpenOffice.org Productivity Suite - can be used for word processing, spreadsheets, presentations, graphics, databases and more. See review here.
Create you own animations with this free open source 3D animation package. Blender is a feature rich, free open source 3D content creation suite, available for all major operating systems.
A free personal publishing platform with good aesthetics, web standards, and usability. If you don't have a server to host your site try WordPress.com for a quick blogging solution.
A file archiver with a high compression ratio. 7-Zip is open source software which means it's free. Supports formats: 7z, ZIP, GZIP, BZIP2 and TAR.
Build yourself a content managed website with this open source content management platform. Drupal is equipped with a powerful blend of features and there are a wide variety of modules you can add.
A free, open source content management system (CMS) for publishing content on the World Wide Web and intranets. There are many free Joomla templates, menus, modules and other components.
Apache community of open-source software projects. These include: HTTP Server, Jakarta, Lucene, Perl, SpamAssassin, Tomcat, XML and many more.
A popular free open source database. MySQL is a part of LAMP (Linux, Apache, MySQL, PHP / Perl / Python), which is a growing open source enterprise software stack.
A free, cross-platform sound editor. Audacity is an open source software for recording and editing sounds can cut, copy, splice, mix, change pitch and more.
Creators of the popular free web browser Mozilla Firefox and the email client Thunderbird. Download these and more from their site.