Yesterday I was sent an invitation to Spotify by Sam. Which is a service where you can find, listen to and share music in one place, rather like last.fm.
You just go ahead and download the OSX desktop streamer which has a really nice interface and listen to music from there.

With a free account an advertisement will commence every few songs you play and can be removed by purchasing a premium account but isn’t that bad anyway.
Just likes in iTunes you add and organise playlists.
The interface will also keep search strings open for you unless you close them and the entire application has functionality with the play/pause etc keyboard shortcuts.
So thats my review and thoughts on this service and I’m still impressed with the fact that its so integrated and free.