In case you hadn't heard, Last.fm now offers full song streaming of a pretty huge catalog.
3 streams per song are allowed for free, after that they have some kind of pay service.  Definitely a good way to check new stuff out, and artists get paid based on their popularity.  Me like!  Add some DRM-free high quality downloads, and boom.
I hope that the future of music listening doesn't depend on a reliable broadband connection, though.