Why does Amazon charge 30% less for some CDs ("includes free mp3 version of this album!) than for just the mp3s? Case in point, a back-catalog Dixie Chicks album, $9.99 for just the mp3s but $6.99 for the mp3s plus CD.

My only hypothesis is that they want to get rid of the physical inventory, and they're willing to take a loss to do so. Any other guesses out there?

(Yes, Dixie Chicks. I didn't know I liked them until Pandora sent them my way. In the last three months I've bought about a dozen albums from groups I never knew I liked because of Pandora, which I hope helps the musicians a little bit.)