having less spam in comments ?

[badg3r]

would it possible to add some "security" field for the comments ? I mean something like a random number shown that must be written in a field so that most of the robots won't be able to post automatically comments.
The spam filters are working correctly at the moment, most comments with spam are blocked, but they still show in the moderation list. It would be best if they wouldn't come at all...

[Jeppe]

There's a simple captcha now in hopes of reducing at least some of the spam.