InsaneJournal Announcements

You may want to try implementing a honeypot. This would likely go a long way in preventing bot comments (and could also prevent bots from registering and/or logging into the site if you implemented it in the sign up and login forms, if you wanted to go that way.)

Like with any anti-spam method, there are disadvantages to honeypots, but I think it's worth looking into since the amount of spam coming through in the comments is so high. I know, for me, my main journal here and my layout preview journals have been getting hit pretty hard.