I just stumbled upon this gem today, and I wept for having only found it now, at the tail end of Burning Crusade.
REQUIRED. READING. PERIOD.
Angry Raid Leader
WoWWiki states..."Aggro is understood to be the condition of a particular mob attacking a particular character", others use it as an abbreviation for "aggressiveness". I like to think of it as "aggravation", and I've got plenty of that...