Many people think arena is boring, since once you die you are dead.
This may be a way to make being dead not boring:
Similar to Mario Karts Balloon Battle-stuff, players who die respawn as ghosts. They can then fight against other ghost, while they can not interact with "living" players(bullets etc. pass through them). Ghosts CAN see living players, but living players can't see ghosts, so that they won't be distracted. Ghosts would probably look like the characters with a some transparency.
I am aware that this is a lot of wok for trivial stuff but it would be kinda nice.
This suggestion is not related to CoD: Ghosts in any way.