Mentioned this briefly to Nef in-game, but wanted to elaborate here.
My idea is a sort of minecart jousting match. The entire thing takes place between two people in minecarts (leaving the cart would be a disqualification).
The two combatants are outfitted with swords, bows, and 10-15 arrows each. They each then get in one of two carts (which are divided by glass wall or somesuch) and a third party launches the carts via button. The carts shoot out and begin racing along parallel tracks that have a number of ups, downs, obstacles, and turns. It doesn’t matter what shape the overall track is, as long as the carts are covering roughly the same distance each so as to stay near each other–in my head, the carts are spiraling around the edges of the square lot from top to bottom, switching sides as they go to stay roughly level with each other. During this time, the combatants can use their bows and arrows to shoot at one another or their swords to clash in melee if the carts ever get close enough together.
Once the carts get to the bottom of the lot, they engage a central set of loops that bring them around in long ovals, right next to each other for half the loop each (imagine a more traditional horseback joust for this part, where the contestants constantly take runs toward eachother at close range). The carts will continue looping here until only one combatant remains.
That’s the general jist of it, and additional tweaks could be made, including targets that when shot, drop healing food, potions, or armor onto the shooter’s tracks. Perhaps there could be buttons to release mobs or animals onto the tracks also (though that might spoil the whole premise).
Lag might make this idea a little less feasible, but overall it could be a fun experiment. I would of course volunteer to build it if I can peel myself from Diablo 3 for long enough to do so.