What about a "Report post" link?
I've seen this feature/function on a few boards and it's a good thing. What it does is that it allows users to report a post which they for some reason think a moderator should take alook at. The result is a sort of global pm (with a short message which the reporter writes) that the moderator(s) that's currently online sees, or the first moderator to come back if there is none present at the moment. The good things is that the psot will evaluted faster then by usual PM'ing (as the moderator to who the PM arrives might just be getting off line, resulting in that the time till the post is looked at might become longer.
something i'd hope we'd never need
that's the sort of feature that would be nice, but would be a shame if it had to be used a lot. :(