Allow players to set their own ability to hurt or be hurt in PvP, by chat command or by pressure pads. Nametag colour changes to reflect status.
Excellent safety net for less combative players.
Works well, allows server to be run with PvP enabled but without players always at risk of being killed.
There is a conflict with the protectors mod, unless you disable protection from PvP within the protected area. Not a biggy as long as you know.