Reading this article made me laugh just now. Uninstall Norton Antivirus on mac... Double whammy. Interestingly enough though a lot of universities seem to provide antivirus software for mac, even though the version might be a bit more dated than the windows version. NO thanks Norton.
Though actually I would say that norton is ok that it comes with an uninstaller. Something that's particularly hard to uninstall in my opinion is silverlight. I downloaded the latest beta once, to check out their facebook application but I realized I didn't like it so I wanted to roll back. To my dismay when I searched the website I realized that I have to manually delete the files from specific folders or else when I try rolling back, the install dialog would say that I have a never version available. Would be much nicer if microsoft had an uninstaller for silverlight, kind of like what flash has.