I tried out Spotify, and I'm now on their premium plan! I like having access to all sorts of music, in high quality, over a number of devices. There is a free version that you can sign up for, but it might take some time to get an invite.
Diana is covered quite well. You can even get Diana karaoke tracks!
I learned a lot from this this interview on Kojo Nnamde on WAMU in Washington, DC (NPR)
A Turning Point for Online Music:
http://thekojonnamdishow.org/shows/2011 ... line-music