Moderators mark threads as checked
 

I have a couple of forums where the moderators look over the threads for certain information. The problem is that they don't know if another moderator has already 'checked-off' on a thread. They would like it if a thread can be flagged to say it is OK. However, I only want other mods to see that the thread was already checked, not the users. I also don't want to put the threads into a mod cue or anything like that. Everything should appear normal to the users, I only want to either color the thread title or put a dot next to the thread title or do something in the threadbit that marks the thread as already OK'd by a Mod and that mark is only viewable to the Mods.

Does anyone know of something kinda like this or have a suggestion on a similar hack that I could modify to use?