Sorry I missed this, I took a server break. Can someone give a quick overview on the proceeding? Is there a posting on it some where's?
From what I read and understand in this thread, I would make these suggestions.
Put some pens with doors in the arena for monsters, put monsters in there hostile and then open doors to begin fight? Maybe even there could be an accident, a few monsters escape into crowd

, munch some low class spectators (bringing infamy to the contest which should boost interest and attendance even higher, think of it like the running of the bulls...

)
From the way I understand there was no scaled categories? Levels to 10, levels to 20, levels to 30 sort of thing? Throw in level one's vs one's? To get the right PvE levels might be difficult... course pvp would be easier in this regards.
Mage vs Mage or spellcastor only category and such...
If crowd is unhappy, what do they throw? no tomatoes in ud
I prefer a gladiator class vs. , in this case we don't have a custom gladiator class so make it Barbarian or Man-At-Arms maybe. You have to start fist 3 lvls at this base class, then you can select a second class. It would be most interesting to see starting lvl one with some + hitpoint armor so you don't one shot each other then seeing these players advance through with only XP given to 1, 2, 3 places proportionately by DM. These gladiator specialists would put the name "Gladiator" behind their first name, just to give an interesting twist to the events. So obviously these contestants are not fight to death, if other concedes defeat or is unable to continue, they are patched up for next weeks battles.
Slaves as Gladiators of course are always a natural thing... different Houses sponsoring various slaves, reward and fame to the House. Maybe to really raise the stakes, the eventual slave gladiator Champion gets the choice of freedom if they so wish. And since mages can not be slaves that eliminates them from entering in this category.
Oh and of course, criminals and, or, enemies of the state will be fight to the death, reward for winner? you get to live to your next fight..

, some such could be arranged for NPC opponents (the tougher ones)
Possibilities are endless here, I can see though how hard it would be to run this by yourself, so hats off to Absolution for keeping it together...
So to sum up something like this:
Category One : Open, any class, any level
Category Two : Gladiators, level one
Category Three : Gladiators, > level one >
Category Four : Gladiators Team, 4 vs. 4
Category Five : Open, Team 4 vs. 4
The MAIN EVENT! : Watch the Champion take on Challenger X