OpenOffice.org
Create documents, spreadsheets, databases,and presentations. This suite offers the same functionality as Microsoft Office and can read and write files in Office format.
http://www.openoffice.org

Scribus
Printer quality publishing application. Create signs, brochures, and newsletters.
http://www.scribus.net/

FreeMind
Mind mapping software. Use this software to do brainstorming or lay out an idea. Similar to Inspiration.
http://freemind.sourceforge.net/wiki/index.php/Main_Page

PDFCreator
Turn almost anything into a pdf file. This program can also secure documents.
http://www.pdfforge.org/products/pdfcreator

Nvu
Website editing and publishing made easy. This program has many of the features of programs like Dreamweaver has a simple interface.
http://www.nvu.com

Firefox
Better browser. This browser is more secure than IE and allows you to use tabs to view multiple pages.
http://www.mozilla.com/

Thunderbird
Thunderbird is a mail and news reader with much of the same functionality that Outlook has.
http://www.mozilla.com/

Cd Burner XP Pro
Not open source, but still a great cd burner. It will burn several types of cd's and dvd's. It will also burn a cd from an ISO.
http://www.cdburnerxp.se/

Wink
Capture screenshots and add notations to create interactive tutorials.
http://www.debugmode.com/wink/

Audacity
The premier audio editing tool. This program allows you to record, modify and mix audio for a variety of projects. It is used to build podcasts and create full length cds.
http://audacity.sourceforge.net/

GIMP or GIMPShop
Comparable to Adobe Photoshop in features, GIMP is an image editing program. For those of you who already use Photoshop, GIMPShop is GIMP redone to look and work more like Photoshop.
http://www.gimp.org/ or http://www.plasticbugs.com/

CDex
Rip CD Audio into WAV files. You can also compress the files using addin programs to convert the files to mp3.
http://cdexos.sourceforge.net/index.html

Edubuntu
Turn an old computer that won't run XP well or that was donated without an OS into a modern computer complete with multiple types of software including Internet Browser, Open Office, and several educational titles.
http://www.edubuntu.org/

MythTV
Create a PVR so that you can record live TV and store your DVD collection for easy playback.
http://www.mythtv.org/