Soda for me and Diet Coke usually means Diet Pepsi when Coke isn't avaiable.
I live in a community of people from all over the country so I'm getting used to hearing soda called pop, but still don't understand it. Something in my memory yells me that when I was very young we said "soder." I guess we grew out of that years ago, though. Maybe we should call all of it carbonated, artificially flavored, non-alcoholic beverage...