The Spousal Unit came home from work the other day to find Overlord Mok'Morokk hanging out in Orgrimmar. He joined the fray for a couple minutes and then started the night's raiding schedule. Hours later, he found the ogre from Dustwallow Marsh still there. Though the battle had been kept up the entire time, the Overlord just couldn't be brought down. All of the bank alts in the AH were subjected to periodic AOE stuns and the constant sounds of battle while trying to conduct business.
Of course, this isn't the first time someone has been kited into a major city for the sake of mayhem. Players have been doing this since the beginning of MMO time. It can be annoying but also breaks up the monotony of the atmosphere. Some, however, view it only as griefing.
What is the most unusual NPC or creature that you've seen kited to a major city? Do you think this kind of activity is fun or annoying? Have you ever had the patience to kite something this far yourself?
Edited to add: Link to a reunion of Jaina and Thrall.