These days there is a lot of talk about spams and what it is and what is affects. A quite comfortable list of available tools is available at "The war on Spam" . But it took me quite a while to find a suitable free product, that also battles against spam mail.
Mailfrontier - a new startup - has made a beta version of its Matador Spam filter availble . It installs pretty well into Outlook 2000 and 2002. Its filtering combined with some standard filter rules leads to admirable results.
Paul Graham has an interesting article "a plan for spam" on spam filtering techniques . David Mertz comes up with "six approaches to eliminating unwanted e-mail" .
I have been using Spam Inspector to control spam for about three months now. I am very pleased with it. One of the nice things is that it is a plug-in to your email client. It can be used with Outlook, Outlook Express and AOL. There is only one other product Im aware of for AOL. The price is reasonable and it catches about 99% of my spam.