MAG is starting to get up there slowly, considering I love spending time with my clan. I know for a fact that I played Socom 2 well over 300 hours. Probably Left 4 Dead too. As you can see, the more team oriented shooters is an addiction to me.
My sister (with me helping her most of the time) has put well over 300 hours into every Tales of game that reached the NA. Her highest right now is Vesperia for the 360 at over 900 hours.