Found this after seeing the article mentioning junkbuster. Privoxy is (according to their website):
... a proxy that is solely focused on privacy protection and junk elimination. Sitting between your browser(s) and the Internet, it is in a perfect position to filter outbound personal information that your browser is leaking, as well as inbound junk. It uses a variety of techniques to do this, all of which are under your control via the various configuration files and options.Privoxy is based on the junkbuster source, has features like browser-based configuration and intelligent filtering, and they have an OS X package available for download. The only problem I had with it was that /Library -> StartupItems -> Privoxy -> Privoxy needed the execute bit set (chmod 755 Privoxy).
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020618210555895