I propose that Blizzard adopt the PVP aspect of the game Nox (or some of their ideas at least) for their upcoming Diablo III. Nox is a fast-paced top-down isometric RPG that was developed and released by the now defunct Westwood Studios in 2000. It sported a multiplayer that gave all players pre-leveled characters who possessed weapons and armor, (evening out the playing field) then dropped them off in an arena that was littered with other items to fight it out until the frag count was hit. Here is a video of the PVP system in action:
http://www.youtube.com/watch?v=KGbJvbDMEf8. Aside from deathmatch and one-on-one matches, Nox's PVP system also supports capture the flag. The implication of such a system of course is that your pre-leveled/pre-equipped PVP character would be separate from your cooperative/single player character.