Interesting, did "Light In The Attic" Records sponsor this list? Quite a few have already gone onto to another career or second wind with the Indie crowd and/or much success over seas during their career or after, even though they may be in the dark to many Americans. I think one omission comes to mind and could have easily been added instead of the laughable inclusion/final selection, Nick Drake's mom:

http://en.wikipedia.org/wiki/Barbara_Dane