A new achievement for killing the top 10 (or so) ranked players.....give it a name like "Scooooore Booooooard!!!"
I think it would be a fun one, puts a "bounty" on the top ranked people(once they either kill or get killed), which makes them have to work harder because you know some would be hunting them once they found them(giving the score system a bit more competition)....I know I would every once in a while to get the achivement, tired of my squaddies making fun of my 2 stars.
Another would be "Bounty Hunter"
I know I personally don't mind that people know where I'm at, maybe make a bounty mode where a player can set it and their icon pops up for everyone on the map, with or without radar(bustr had this idea in another thread). The achievement would go to the kills of the guys set in bounty mode.(maybe setting to bounty mode would count for more kill points) Side note: This one I can already see where people could abuse it so I don't know....maybe.
Just some ideas, whatcha think???