This article contains a list of free and/or open source applications I recommend for various tasks. I use some of them, others come highly recommended. This is current as of January 3, 2010. I will periodically repost newer editions of this as needed. Go to the next page for a full listing of applications.
Anti-Virus
AVG Free (http://free.avg.com/us-en/homepage)
A free anti-virus utility. Once upon a time, it was the most recommended anti-virus software.
ClamWin (http://www.clamwin.com/)
I’ve never used this particular antivirus utility, but I know PortableApps adds it to some of their distributions.
Audio/Video
Itunes Library Updater (http://itlu.ownz.ch/wordpress/)
Free utility that syncs itunes libraries to a set of folders.
VLC (http://www.videolan.org/vlc/)
Free/open source media player
Disk Burning
InfraRecorder (http://infrarecorder.org/)
Great free disk burning utility. It will burn just about anything.
File Compression
7-zip (http://www.7-zip.org/)
Free/open source file compression utility. Supports Windows/Unix/etc formats.
Image Editing
GIMP (http://www.gimp.org/)
Free/open source image editor. GIMP is a full-featured free alternative to Photoshop.
Infanview (http://www.irfanview.com/)
Free photo viewer/batch editor.
Picasa (http://picasa.google.com/)
Free photo library/viewer/editor by Google.
Networking/Internet
Filezilla FTP Client (http://filezilla-project.org/)
Free/open source FTP client.
Mozilla Firefox (http://www.mozilla.com/en-US/firefox/personal.html)
Free/open source Web Browser
Mozilla Thunderbird (http://www.mozillamessaging.com/en-US/thunderbird/)
Free/open source email application.
Pidgin IM (http://www.pidgin.im/)
Free/open source instant messaging application.
Pidgin IM Facebook Plugin (http://code.google.com/p/pidgin-facebookchat/)
Free/open source Facebook plugin for Pidgin IM.
Putty (http://www.chiark.greenend.org.uk/~sgtatham/putty/)
Free Telnet/SSH client.
WinSCP (http://winscp.net/eng/index.php)
Free/open source SFTP, FTP, and SCP client.
Other Utilities
CutePDF (http://www.cutepdf.com/)
Free utility that will allow you to save anything you can print to a PDF. Simply select CutePDF as the printer you want to use.