it's a bit minecraftish to my mind, but l think the way i suggest it, it suits MT better. it's about sorting, yes, but! as the game itself doesn't have that lot of items, but there are plenty of mods, each with it's own items.
so, my suggestion is to implenent categorizing in creative, but it should be mod-oriented.
ps. i already said that i am no programmer, i can't do it myself, just wanted to share the idea.