Idea: At every tier of raiding in WotLK, you get a quest to kill the end bosses, such as Gruul, Nightbane, and Magtheradon for T4; Kael'thas and Vashj for T5; and Archimonde and Illidan for T6. Blizzard already has these quests in game in a roundabout way via the old T5 and T6 attunement quests which grant the Champion of the Naaru and Hand of A'dal titles, respectively. Do the same thing, but without the slightly crazy heroic dungeon parts and attunements (since attunements are hopefully going the way of the Dodo).
The point of these quests would be to grant you a special title, only achievable by killing the end boss of that tier. This would show the server what level of content you have completed.
This stemmed from an idea I had for the title you should get for killing Kel'thuzad: Lichbane. As in, Schmoopy, the Lichbane. I think that sounds awsome, but it could just be me.
Oh man, I so need to name my Death Knight Schmoopy. But no one would get it :(.