You're very naive. Of course there's the possibility of a fanmade NSF (I believe someone on NESDev had made one with 3 tunes from the demo), but ripping proper game music to a NSF is not possible.
No, a NSF for Mega Man 9 cannot be ripped. However, as Knurek said, Acmlm is making a very accurate NSF of the music. I posted some links before, but here they are again:
Mega Man 9 WIP NSF:
http://acmlm.rustedlogic.net/etc/mm9/mm9.nsf
Mega Man 9 WIP Music Player:
http://acmlm.rustedlogic.net/etc/mm9/mm9nsf.nes
I really hope that he finishes this project. He has done an excellent job of recreating the music so far.
Hm, two separate people doing the same thing isn't too productive. Acmlm and Sivak should hook up. Also resulting NSFs should be subject to herculean levels of scrutiny until they're as perfect as possible ;) there could do with being a webpage for it, I imagine it's a project many people would be interested in.