In LFG or LFR people generally offer up items they do not use. at least I do and I've seen others do it. The biggest problem comes with the last boss of any raid or dungeon where people just drop as soon as they loot. I was looking for a quicker way of checking what I get and what others get and be able to message them quickly instead of searching the list of names and either holding up a raid waiting for me or if it's the last boss and people are dropping. I would think this feature could be popular, auto whisper for a request "are you going to use item XYZ? if not would you trade it to me" or a raid chat for an item I don't need "Roll for XYZ if anyone needs"
If this exists I don't know what it's called for an addon, if it doesn't exist, is it possible and will people use it?