The problem with spyware is basically not only the fact that the hackers can track every move you make online they also destroy the advertising market by producing false clicks. The biggest installations from what I hear out of the "scene" are combinations of spyware and adware plug-ins for the Internet Explorer. These plug-ins see when you surf to Google or Yahoo and steal their ads or modify the result pages when you search for something! That is really evil!
I have put a site about online security downloads online where we list our selection of preferred commercial spyware killers and adware blockers. To spice up the pages I have used the youtube plug-in we wrote for tradebit and link to videos for certain products. There is also a link on the right for a FREE scan of your computer.