Amazon is pretty good with their MP3 deals. For a while I was following their MP3 store's Twitter feed, which turned out to be the ONLY worthwhile use I had for Twitter. They let you know about free tracks and album deals. A couple weeks ago I picked up an album for $2.99.

*edit*
I have since stopped following them on Twitter (and everyone else, for that matter). I have it on good authority that there might be a Zune w/Zune Pass in my future