I just installed Jay Allen's excellent Movable Type Blacklist Movable Type spam blocking utility (yes, people have figured out that if you put comments about penile enlargement and the years' hottest toys in old blog messages, they'll probably get ranked higher in Google, while remaining relatively unnoticed to the blog owners/readers). It's yet another content filtration technology and the latest carnivore in the spam ecology. It seems to work quite well and Jay is giving it away, which is great. I'm actually quite amused by the evolution of spam and anti-spam technology. In a sense, it's a microcosm of the kind of content filtering/organization problems that we're going to be running into from here on. It just happens to be at the crudest, most basic level of parasite/antibiotic relationship, but it's also a harbinger of the kinds of attention-getting versus attention-focusing tensions that are likely to only increase.
I also installed Alexei Kosut's MTSpeling plugin, which also works quite well.