Im surprised this hasnt been brought up before, and if it has, im sorry i just didnt see the thread.
In Ul'dah, a few of the quest are centered around the importance of the Colosseum to the city state, but nothing is really utilized at all there. There is a couple quest with gladiator and pugilist that you actually get to go in an instance and fight. What i'm suggesting is, open up the Colosseum to Adventures for PvP. There could be two sides to this instance. Spectators and Fighters, and the adventurers could place bets against each other and npc perhaps based on odds. There could be a wall of fame and everything. Adding nice, never ending content to the already central hub of Eozera.
To the victor goes the spoils. They could make you drop a piece of gear for losing, or simply drop a piece of job specific gear, perhaps even make this action cost guild marks and also reward with guild marks.
:cool: