I agree Rowling should do more than the planned 7 Potter books. I think there are a lot of great stories still in that world. I read an article in Time (I think) a while back where she already has a book in mind for after she finishes the 7th Potter one - in a different genre entirely although I don't remember what. She said that she was tired of writing fantasy novels. \
I am reading a novel called "War Trash" by Ha Jin and it is the story of a Chinese soldier captured by Americans during the Korean war and his struggle to survive being a POW a dealing with the two Chinese factions in the prison camp - the Communists and the Nationalists. It is written in the style of a memoir and is a very good read so far.