Grooveshark takes the iTunes experience to the cloud

Music technology continues to evolve. From the wax cylinder to the record, to the CD and then to the iPod, the vehicle for the sound has become increasingly immaterial.
The latest generation of streaming music services even removes the need for local storage: you simply search a cloud-based library and pick out whatever you fancy.

In my experience the most satisfying of these sites in the wonderful Grooveshark, an online application that provides an iTunes-like interface for listening to and sharing music as single tracks, albums and playlists. Alongside listening on the site Grooveshark is also great for embedding and sharing tracks through Twitter, Facebook etc.
Here's an example, taken from Dirty Projectors' excellent Bitte Orca LP:

Dirty Projectors - Bitte Orca (2009)

What really makes the service stand out is not only the range and depth of music available, but its openness. Spotify is similar, but only provides service to Scandinavia, Holland, France and the UK. LaLa is US-only, and has nosedived since being acquired by Apple. Last.fm is very strong on community features, but only streams free to the US, UK and Germany; its library is alo very limited, usually only a few tracks at a time.
In contrast, Grooveshark looks like a glimpse of the future. According to Crunchbase:

Grooveshark also allows artists and record labels to promote themselves through the application with both advertisement and paying for listens from Grooveshark users. All data and analytics relating to an artist (or group of artists) are freely available to promoters, such as the number of times their content has been listened to, along with demographic and geographic information about the listeners.

So I get free music while the artists get an insight into preferences, listening habits etc. All valuable data.

Grooveshark (headed by the wonderfully named Sam Tarantino) currently has deals with EMI and some smaller (mainly indie) labels. Whether the big boys play ball is still open. So try it out now before the men in suits come and spoil the fun. Even if they do, they will only be delaying the inevitable.