I only have one thing to say. If you use MovableType, go download Jay Allen's new MT-Blacklist plugin and implement it asap. Jay put an awful lot of work into this plugin and he should be commended (hey, tip the guy will ya?!). It's technically in beta, so if you aren't comfortable with doing it all over again (potentially) at some point or having a few bugs here & there, I guess you can wait. But you shouldn't.
I've gone through the plugin and I'm getting ready to install it here. It looks really well done and I don't expect to have any problems, but you know rule #1 around here: If the blog is all blown to hell … it's probably
my Merrin's fault.