hmmm, I could give it a shot. Just thinking about an instance situation where mousing over a pack of 5 mobs would be difficult to discern.
I have in mind something that will actively scan mobs in aggro range and give me a list of targets and (ideally) throw up an assist window next to the palyer's image.
So in my group of 5, I should mostly see a mob-target window next to the MT. If the priest were to acquire aggro, the mob's target window would appear next to there name.
I ran across Banzai Alert. Does it offer this type of functionality? I am not at my system or I would be testing it myself.