RewriteEngine on
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http://(www\.)?mydomain.com/.*$ [NC]
RewriteRule \.(gif|jpg|js|css)$ - [F]
I've had similar problems at times. In fact, a couple times, the situation kept me from gettin' mod points for a while.
I think a good way to tackle the problem would be to temporarily remove mod point privileges from moderators who have given 'troll' or 'flamebait' votes to comments that have a strong amount of 'insightful' or 'interesting' votes. I'm sure the moderation system can be easily modified to check for that and automatically take that action. The moderator who's been affected negatively should be allowed to appeal it I think, by providing an explanation for their vote if they want to. This way, those who are abusing their voting privileges can learn to how to use it and they will be a little less trigger happy and a little more thoughtful before making a moderation vote.
No amount of genius can overcome a preoccupation with detail.