For friends that need to measure manliness a dueling area would be sweet. Maybe use the iron banner area for challenging ppl to duels as an interact option. Just make lord saladin appear or vanish as nessicary. Just a thought.
I think a one on one option would be good. Be able to modify some options. And as people below are saying, have an in game request option and the ability to ignore. Am arena where people can spectate is a ceazy idea as well!