Ad-aware
http://www.lavasoft.com
CWShredder
CWShredder is a small utility for removing the nasty CoolWebSearch browser hijacker and its ever-changing variants from your hard drive. http://www.intermute.com
Diet K
Diet K is the original, award winning, free add-on for Kazaa Media Desktop! http://www.dietk.com
HiJackThis
http://www.spywareinfo.com/~merijn/
SpyBot Search & Destroy
Spybot - Search & Destroy can detect and remove spyware of different kinds from your computer. Spyware is a relatively new kind of threat that common anti-virus applications do not yet cover. If you see new toolbars in your Internet Explorer that you didn't intentionally install, if your browser crashes, or if you browser start page has changed without your knowing, you most probably have spyware. But even if you don't see anything, you may be infected, because more and more spyware is emerging that is silently tracking your surfing behaviour to create a marketing profile of you that will be sold to advertisement companies. Spybot-S&D is free, so there's no harm in trying to see if something snooped into your computer, too :) http://www.spybot.safer-networking.de
SpywareBlaster
Prevent the installation of spyware and other potentially unwanted software! http://www.javacoolsoftware.com
SpywareGuard
A real-time protection solution against spyware! http://www.javacoolsoftware.com