I've seen a thread like this before, however it wasn't very useful. What I'm looking for here is a plugin that allows you to put a crafted item (iron pickaxe, jack o' lantern) into a crafting table, or anything else, and it gives you the materials needed to craft it. (iron pickaxe - 3 iron, 2 sticks, jack o' lantern - 1 pumpkin, 1 torch) The only way I could see this working is if it was put into a dispenser, and the dispenser shot out the materials. Unless you can have multiple crafting results in the crafting table.
I'm not releasing anymore I'm just going to WIP it. @Cilerba : It's working fine (at least it seems that way) Check the WIP section soon for the thread. EDIT : http://forums.bukkit.org/threads/wip-mech-uncraft-v0-1-uncraft-tools-and-blocks-1000.31386/