it seems cyclone has some points there
another idea though might be a "summary only" thread, where in each post, the chapters of the manga a summarized - so it would basically be a ressource for people new to the story (who'd get spoilerd that way so its not so much good in that regard) or it might serve as a ressource thread for discussion, where you can quickly look up in which damn chapter that scene was that you remember but just can't place.
There still would be the problem of how to manage that thread and of how to decide which one ultiamtely gets the "final" summary that than becomes canon so to speak
I guess I like the "post /relink others people's noteworthy theories" idea from cyclone most so far ...