imfSpamFilterPlus
Normally, when people think about spam filtering, they don't think about Exchange's Intelligent Message Filter.
Rightfully so, because most people who are in the know are probably running SpamAssassin for their all their spam filtering needs. But as anyone who has had to administer Exchange (and I do feel your pain), trying to shoehorn SpamAssassin onto Exchange is roughly equivalent to trying to remove your own uvula through your nose. And IMF has some serious shortcomings, like missing whitelist functionality, and an all-or-nothing approach to its levels of spamminess.
Now, there are costly alternatives that you can run on top of Exchange+IMF to get these functions. But, spending $395 or $19.95 for something that doesn't work very well in the first place just seems wrong. I mean, think about how much beer you could buy with that!
Thus, the imfSpamFilterPlus was born. It's not the most efficient piece of code (it's written in JScript), it's not the best performing (it uses regular expressions), and it's not slick (it runs from the command line or from Scheduled Tasks). But what it does do is give you an alternative to pressing your fingers on your eyelids and watching the pretty colors while pressing the delete key on all your V1@g4Ra spam.
vorbau designed it, including the whacky keyword ranking system.