A type of terrain that allows items to fall through but people and monsters can still walk on it. For example, You kill a monster that is on this terrain the item it drops falls through. This could be useful for people that use water to gather up dropped items. just put water under this terrain and boom. Instant conveyor belt.. Kinda. I was thinking of some kind of metal with holes in it.
http://www.youtube.com/GothamCityPanda
I couldn't think of the word, yes a grate. Rofl. One for the spare change of zombies and other creatures to fall into for my taking. Mwuahaha!
http://www.youtube.com/GothamCityPanda