Spam, spam, spam
Pdawwg: A Proposal!!!. Pdawwg loves the spam he gets! He should try popinfo at Sourceforge. It is the most active project on Sourceforge and it is amazingly hard to install. On the other hand, it is right now 98% effective and rising in getting rid of spam. BTW, on my email@example.com inbox, spam is running 80% of my total mail.
How does it do it? Bayesian probability. Much more elegant and mathematical approach than I've seen from Brightmail, Cloudmark. This could be another example where mathematics and science beat engineering hacks. Reminds me of the google vs. yahoo wars. Google has some science, yahoo has elbow grease.