This plugin, called BattleNight, looks like a really cool plugin, and with this plugin, we could have controlled teams for PvP! It would just be a fun little gladiator sorta thing. Here's the link to the thread: http://forums.bukkit.org/threads/fun-battlenight-v0-9-battle-your-friends-and-foes-perms-1185.33802/ EDIT: Also, here's the link to MobArena, A Player Vs Enemy plugin: http://forums.bukkit.org/threads/fun-mobarena-v0-94-3-11-become-a-mob-fighting-gladiator-1240.19144/ 2ND EDIT: It seems that BattleNight is unaccessable. I found another plugin like it, but it is only updated to build 1000.
Interesting, the pvp one would be something I would think about since we are having night time right now. The mob arena looks like monster hunt, which was removed.