Just started using pop3proxy, a SpamAssassin pop3 proxy server that's usable on Windows (like, wow). It looks very promising.
And here I thought I had to write one myself :) Monk McD++
Of course, my second thought was to build some kind of tray-gizmo to monitor the proxying and despamming of my beloved mail. And maybe, if it's okay with McD, build an .exe distro so the just above average Windows users can install it as well.
Making Perl look good, that's good.