i want a new half life
also how could i forget mass effect 2, i'm completely addicted to the first one right now!!
modern warfare 2 will probably be great but i haven't beaten the first one yet, i'm slow with some games. 
MW1 really caught me by surprise. I was like you, actually. I played a bit, did multiplayer a lot and got tired of it. Then; one day I decide to go back and play through all of the single player and was completely blown away. I was expecting generic patriotic tripe...
I just beat mass effect 1 too by the way, strange coincidence... Though I did just beat it in a week.