Blip.fm is a microblogging service very similar to Twitter, but lets the user attach full streaming songs to their posts.
Blip.fm turns you a virtual DJ - whatever you share becomes available to the community and others can listen, bookmarks and give you props (tokens of respect that can be given from one DJ to another).
When you signup, you are wired to DJs with a similar musical taste. Also you can buy the MP3 from Amazon, directly from the posts. Thus unlike Twitter, Blip.fm is microblogging with a focus on the musical community.