I saw a pretty simple, yet still amazing and in my humble opinion quite effective means to deal with comment spam the other day.
The blog in question (http://snookerblog.de; it's in German) is powered by Textpattern, and it's commentform disables the send button unless the user has clicked preview first. I don't know how they do that, but I think it's pretty effective against bot-generated comment spam - or is there something I don't see? Bots can't click buttons, right?
Do we have something like this? I don't think so. I also think it's a great way to deal with comment spam without wasting any kind of ressource like blacklists or askimet. However, it can be quite a hassle for users ... so what do you think about this? (No, I can't write a plugin for this myself. Still.
)YL