Below you will find lists of useful software that I use on a regular basis.

Free and Useful Software
Google Chrome Web Browser Probably the best thing you can do to improve your security online is to stop using Internet Explorer on a day to day basis. Don't bother with Firefox either - it became slow and buggy. A better browser is Google chrome.
Comodo Personal Firewall This is a very good personal firewall program to protect your PC from hackers. 
AVG Antivirus As well as a firewall, you need Antivirus software if you are connected to the Internet.
AdAware This one will remove spyware and other nasties from your system.
Spybot Search and Destroy This one removes even more spyware and nasties from your system.
Pixory Pixory Image Server. Allows you to broadcast photo albums from your PC. Used on this site.
StartEd Shows you what is really running on your PC at startup, and allows you to get rid of that junk!
Disk Scanner Want to know what is eating up all your hard disk space?
Google Earth View the Earth in 3D. This program allows you to zoom in on the World and view a huge database of Satellite and Aerial images.
WinAmp An excellent MP3 audio player.
Webcam2000 Great if you want to grab images from your video capture card and broadcast them on the web.
WS-FTP The best FTP program available.
Winzip The best zip / unzip program out there.


Not Free, but Worth the Money
WebcamXP Allows you to stream a live webcam. I am using it on this site.