If anyone has played the Knights of the Old Republic RPG, I'm taking a page out of their arena matches, as well as the WOtBS Player's Guide.
Essentially, for nonlethal combats, there is a powerful spell on the area which converts all damage into non-lethal damage. So, essentially at that point, the crowd may influence whether your next match remains nonlethal. Too many repeated losses or poor performances and they may remove the barrier to renew interest in your fights.
Which reminds me, I am thinking of a very, very minor houserule.
I want to add another Perform skill. Perform: Gladiatorum(or something to that effect), essentially representing one's ability to work the crowd. There was a really good article on it in a recent Dragon issue(pretty sure it was dragon), and I'm wishing I could find it... I plan on adapting some of it.
Essentially, for nonlethal combats, there is a powerful spell on the area which converts all damage into non-lethal damage. So, essentially at that point, the crowd may influence whether your next match remains nonlethal. Too many repeated losses or poor performances and they may remove the barrier to renew interest in your fights.

Which reminds me, I am thinking of a very, very minor houserule.
I want to add another Perform skill. Perform: Gladiatorum(or something to that effect), essentially representing one's ability to work the crowd. There was a really good article on it in a recent Dragon issue(pretty sure it was dragon), and I'm wishing I could find it... I plan on adapting some of it.