Ok, just to expand a little more on the Colosseum idea this is what I personally have in mind.

The area would be its own zone, however, it would be able to be accessed by anyone at any given time without any fee to enter. Within this zone, you have the main entrance where there will be several NPC systems that are there to display several bits of info.
1 : Rankings
2 : Match Schedules
3 : Registration
4 : Gil Bets

The area would then fork off into 2 directions, left and right, and each direction splits into two choices. Each will lead into its own little "box" where you can view the match in front of you. There will be up to 4 matches possible going on at one time. Similar to prankration.

1: Rankings, obviously would display the winners of all the matches and would serve to display tournament progression if needed.

2: Times of the matches to be had. Name vs Name @ 12:00 Vana Time or w/e

3: Registration NPC would allow you to register in a match, you can set it to be 1 v 1, 2 v 2, or 3 v 3, lvl caps, etc.

4: This is the good part, people can willingly place bets on the matches outcome! Gil Gil Gil

Skipping back to the layout, once you register, you are allowed to roam the area and view matches till your turn comes up. Once it is time, you will be warped into a small room, and within that room will be a NPC that will sell to you ( using special Colosseum points ) temp items(potions, ethers, no giants drinks or broken junk), buffs(pro shell haste according to lvl cap). Then once the match begins, a door opens up and you pass through to face your opponent.

Once the match is done, the winner will win some of the gil from the bets, and will earn credits within the Colosseum that can be used for the buffs, and stuff, and also new PVP type ARMOR and WEAPONS!

These weapons and armors can be augmented using the points as well with buffs such as ice spikes, counter, dmg taken, mdt, etc. blah blah blah

So yeah, SE gimme this now!