Ok, so this is just an odd thought from me.
During the campaign, there's a part where you're supposed to kill guards to prevent them from blowing a warning horn. Being the kind of person who has to push the button, during my first campaign I killed the guard and immediately proceeded to blow the horn myself.
While I got some sense of satisfaction out of being pointlessly brazen in my approach to the chapter, was I the only one who was disappointed that there wasn't a minor achievement for it? I half-expected a little icon to pop up with something like "Toot Your Own Horn - 10"
Anyway, just my thought. That would of amused me more than a 50 point achievement for killing a random player online.