[Request/Help] Ability to rename blocks/items

Hi there. For quite a while now i've been trying to figure a way to change an items in-game name. Preferably multi-world supported. I'm not quite sure if BukkitContrib can do it, if you can do it without it, or if there is a plugin I just can't find. If you know how, please respond! Many to whoever finds it first. And if you can't figure it out, well...