1.- Sort members (actually everyone should be able to do this, healers would love giving the main tank the F2 for instance).
2.- Flag members, like in PVP arenas but with more options (several colors or icons), making easier for everyone to recognize roles and groups.
3.- Kick members even if they are not in a public instance, let's say instant teleport to quest entrance plus standard kick. It can be controversial but who hasn't seen someone who messes things up constantly or acts inappropriately? It could be used as a tool for evil purposes though (like kicking someone right before looting for plain revenge or whatever, I know there are childish people around :P).
I've always missed these three things ans I guess someone must have mentioned this before; they are not really necessary but they would make life easier.
What do you think? Would you add anything to the list?