NANA the Movie
I saw the movie last month, but had completely forgotten to write about it. It basically covers the contents of Vol. 2 through half of Vol. 5, with the Nana Osaki story in Vol. 1 explained in flashbacks.
I enjoyed watching it. They had the actors/actresses really try to look like they do in the manga (although Shin-chan kinda looked too old to be 15), and they do play their own instruments in the concert scenes. I wished the concert scenes were a bit longer though. (I wanted to hear more of the rock tune Trapnest initially performs!)
And since the movie is doing so well, a sequel will be made.