One thing I really hardly ever seen on a server is a command that allows you to team with people, meaning making it so you can't hurt them! Some things that could be added to this is, a colored name to indicate he is your on your team or clan, maybe in chat it before your rank it shows what clan you are in? I'm not sure but all I can say is if there are places to recruit people for clans I think the /team command would be very useful, that way when your pvping, you won't accidentally kill your teammate. Just a thought :P
Support! I hope Noobcrew or Cypriotmerks adds this to kitpvp and op pvp. They have /party on prison and factions tho, which is pretty much the same