Joni Mitchell is in the pantheon of musical gods. (to read her current dispute with Bob Dylan is like watching Zeus and Minerva argue) This week I feature all Joni music but with no Joni voice: these songs are all covered by someone else.

Some covers seem obvious: Sarah McLachlan sings "Blue," KD Lang sings "Help Me," Cyndi Lauper sings "Carey."

Others sound crazy, but work well: Prince's version of "A Case of You," Brazilian superstar Caetano Veloso's "Dreamland," and Richard Thompson's "Black Crow."

Some follow the originals closely, perhaps with the sense that there's nothing to be improved upon. Some create new music with Joni's classic musical ideas.

After decades of heavy smoking, Joni's voice has dropped about a half octave (though she denies this), and so it's good to hear these songs with the freshness they were orginally crafted with.