What I did a long time ago was that I had a plugin in Winamp that transmitted all the music I played onto a server which I controlled. That server processed the information, got a thumbnail from Amazon.com with web services and uploaded it to this site onto MP3 I Play
With Audioscrobbler they've taken this whole thing seriously, done it much much better and opened it up to the public.
Musical Profile. Statistics from your Musical Profile are shown on your Audioscrobbler User Page, available for everyone to view."
Audioscrobbler appears to be based in London, UK and it appears they're using PHP and Java for their back end stuff. It makes me happy also to read that:
"Audioscrobbler plugins are all Open Source. We're not keeping the data to ourselves either: Anonymous Audioscrobbler listening data is released under a Creative Commons License."
I'm really quite impressed. There's little value to the individual for using Audioscrobbler except maybe the fact that you can match your music taste with other people and that way make some new friends. Good work guys!