Amazon has com up with an interesting approach to using twitter: they broadcast daily deals on music.
I think this is well done. They don’t abuse twitter or their followers because they are limiting it to one broadcast a day. And they are letting people in on good deals, making it more likely that people will want to follow them.
If you are interested in what they are doing, or want to find out more about the deals, see Twitter / amazonmp3
Smart People I Know 