Note that some “free software” lists are what I consider misleading, in that they point to free downloads of programs that you then have to pay for after a two-week trial. This list is of actual freeware that you can use forever without charge. In some cases, the provider sells a more fully featured alternative, but the free versions here are completely functional.
AVG from GRISOFT is a free antivirus for Windows & Linu personal users. Avast makes a free home version too.
Spybot Search and Destory is a free anti-spyware tool.
Ad-Aware Personal from Lavasoft is a free Windows spyware detection and removal program.
Smart Defrag is a free disk defragmenter that lets you schedule defragging so you never have to remember to do it.
Secunia is a free online check to see if you are running old versions of programs that contain security vulnerabilities.
ZoneAlarm is a free firewall program for Windows (2000 & XP) personal users.
Gimp.is a free graphics editor with most of the features of PhotoShop, for Windows and Linux and Mac.
SpamBayes from Sourceforge is a free spam-filtering add-on for Microsoft Outlook.
Open Office from Sun is a free Office Suite for Windows (2000, XP, NT), Linux, Mac OS X (under x11). This suite includes Writer, Impress, Math, Draw, Calc, and Base. Now that Microsoft charges more for Office than a cheap computer costs, people should be aware of powerful and free alternatives.
Pidgin is a free Instant Messaging program that lets you talk to AIM, MSN, ICQ, and Yahoo Messenger friends from a single Windows program. Trillian Basic from Cerulean Studios is another choice, but Pidgin allows better blocking of IM spam (spim).
Firefox is a faster, better Internet browser for Windows, Linux, and Mac. Hundreds of free add-ons. Tabbed browsing and the ability to find favorites just by typing a partial phrase in the address bar are just two of the long list of features that make this much better than Internet Explorer.
Thunderbird is a free Email program from the makers of Firefox, for Windows, Linux, and Mac.
Lightning is a free Calendaring add-on for Thunderbird. Thunderbird, with Lightning, provides much of the functionality of Microsoft Outlook, but for free.
Ultra VNC allows free control of your PC remotely and allows direct Windows-to-Windows use. LogMeIn Free allows control of your Windows computer from any web browser. These compete with paid products such as Link2PC ($7/month), LogMeIn Pro ($13/month), and GoToMyPC ($20/month). Crossloop is a great free desktop sharing tool.
Desktop sidebar software is handy and free.
Google Earth lets you explore the Earth, Moon, and sky for free.
SpaceMonger from Werkema lets you find out where your wasted disk space on Windows systems is.
Stickies gives you sticky notes for your desktop and can even pop up notes for specific web pages.
Visipics is a free duplicate photograph finder.
Computer wallpaper for free.
QTTabBar adds tabbed browsing to Windows Explorer. The same outfit also makes QTAddressBar that adds the Vista Address bar to Windows Explorer in Windows XP.
Free Media Players
Winamp Basic from Nullsoft is a great free MP3 player for Windows.
KM Player is my favorite free video player, capable of playing divx, Quicktime, and others. (Divx is to video what MP3 is to audio–it compresses files to a more manageable size.)
Free Website Setup
Konvenient.com offers free, ultra-convenient website setup.
General Freeware Help
Ninite is an ultra-easy way to download and install a good number of freeware programs–Including AVG Antivirus, Open Office, Firefox, and many more.