If anyone is familiar with the YayHooray catagorisation system, this would be a great help as you will probably be familiar with what I am talking about.

I like the YH catagorisation system, as it is a cross between subcatagories and tagging (it supports both). I always use the discussion list as the default view and I prefer the way that vanilla is discussion oriented and not catagory oriented, BUT, with the varying content on MY forum I NEED to be able to sort/ filter by catagory as sometimes I can't view things at work or school, etc.

Basically, the YH system works like this: (one example)

Meaningless <-- Top Level Catagory (selected from predetermined list)
-- Too Hot For The Internet <-- Sub Catagory (selected from predetermined list)
-- NSFW
-- Stupid
-- Offensive
-- Really Stupid
-- Other <-- Sub Catagory (displays an input box for user input, i.e. a tag)

I don't have the understanding of the framework to create this, but this is something that I would love to see.