a cool idea which extends the report post system
 

I looked but it didn't seem anything even remotely like this existed.

I'd write this myself but I am busy and don't even have the coding skills to make it, at least not a neat/efficient MOD.

You could expand the report post system to track how many times a post has been reported. Once it reaches X threshold then it is red-flagged somehow (possibly by a prefix added to thread title as not all of us use post icons).

You could add in bells and whistles such as optionally setting an X threshold for the report to even warrant a review (lower than the X threshold for a red flag).

This is just the basic idea, you could make a really involved and cool MOD on this. I've even seen requests in the vBulletin suggestions forum for like allowing moderators to keep track of who give out infractions, etc.