I, too, thought of a few more names for you, Naughty, but not all are available on youtube (that I could find). Perhaps, youll have better luck.
Two of these singers are dead, too; one, tragically, was the youngest of the lot Eva Cassidy.
Here she is, singing
Over the Rainbow
http://www.youtube.com/watch?v=tVe_Wa-aV-M
The other, late singer is Kate Wolf. She wrote, among other songs,
Across the Great Divide. Heres a live version, as done by two more, great, female folk/pop singers from the era youre interested in, Nanci Griffith and Emmylou Harris.
http://www.youtube.com/watch?v=iZmbFZHc4Mw&feature=related
The Nanci Griffith/Emmylou Harris duet originally appeared on Nanci Griffiths astonishing album from 1993,
Other Voices, Other Rooms, in which she also dueted with (among some, famous others like Bob Dylan) two more female folk artists from the period you might enjoy, Carolyn Hester and Iris DeMent.
She covered some great songs on that album. One was a knockout version of Townes Van Zandts heartbreaking
Tecumseh Valley (recorded with Arlo Guthrie). Here she is, singing that song (minus Arlo) in another live performance.
http://www.youtube.com/watch?v=Lhxa_qOdNr0&feature=related
The last female folk/pop artist Ill recommend to you today is Buffy SainteMarie. Shes, happily, still alive, and in December 1969, she came out with one of the most amazing albums of all time,
Illuminations.
Illuminations (Buffy Sainte-Marie album) - Wikipedia, the free encyclopedia
This groundbreaking album has at least two of my favourite songs on it, the incredibly sly and sexy
Guess Who I Saw in Paris, and one that, perhaps, should be rereleased to take advantage of the current craze for all things undead,
The Vampire.
The albums completely overthetop lyrically, and productionwise, years ahead of its time. It might be available, in some format, from Amazon. Here, for the moment at least, are the creepy, Edgar Allan Poelike lyrics to
The Vampire, as follows:
The Vampire
Shall I tell you of the night?
It was long ago
Late November, and the snow
Just about to fall
The moon was big and bright
Cold and sharp and clear
And the air was biting.
Softly, swiftly down the road
(Never made a sound)
Someone came from far away
Someone tall and old
As I looked into his eyes
No reflection came
And I gave him bedding.
Oh, my little rosary!
How I miss you so!
Never used you very well
Now, I never will!
I am farther from you now
Than the two ends of eternity
Now, I do his bidding.