Recently, a lot of guilds have been having some problems with Doom Lord Kazzak. Not on the actual fight, which isn't that difficult. Instead, players (of the same or opposing faction) have been flying above Kazzak, getting killed from his AOE shadowbolt and healing him, effectively griefing the raid.
A forum thread from a few months ago brings up possible solutions to this problem. Generally, if you're on a PVP server, this isn't considered griefing because you can kill the other faction before they get in range. But on flying mounts, this is a bit tougher. Someone suggested staging a raid on Honor Hold/Thrallmar to distract possible attackers before you attempt, which is a nice idea. You can also send up shadow priests or mages to POM/pyro them before the fight, or just kill them until they have ridiculously long rez timers. If you're doing this on a PVE server -- or doing it to someone of the same faction on any server -- that's considered griefing and is reportable.
Other people suggest that Blizzard solve this problem through game mechanics. For example, they could make Kazzak's AOE shadowbolt target only members of the raid who engaged him, or have only deaths in that raid heal him. But this sort of ruins the idea of world bosses, where you could theoretically get everyone on an entire server to come take down the boss (or fail to take it down, as was evidenced when Highlord Kruul visited Azeroth.)
How do you think this problem should be solved?