Like a buddy system where you add them and they show up a different colour on your mini-map, ofc, it would only work if they were on your team but it makes teaming up ect easier since i play with my cousins...
First person spectation option ~ Makes playing arena fun i guess, you can then spot hackers easier, if they have some sort of aimbot which like varies where it aims... Shows how awesome you are ;) and it's pretty much a standard in FPS...