A thread about female vocalists not mentioning:
Sandy Denny (of Fairport Convention) and
Linda Thompson (new album out: Versatile Heart)
is not worth to be called a thread about female vocalists. So there.
As for acoustic remakes (not female, sorry): how about Richard Thompson's acoustic version of Oops, I did again
(I kid you not) from the album 1000 years of popular music
(which might just be the best idea for a concept album. ever.)?