Hi, I was just wondering how you would go about making a music visualisation (http://en.wikipedia.org/wiki/Music_visualization) found in today's media players? Does any one know how hard this is or has done something like this before. I am hoping to make this in Java 2D which I a have used before but I am not sure how music visualisation are made. Does any one know of any tutorials or working examples that I can look at? Thanks for your time

I don't know about any articles/tutorials or how to do it, but I know that you can program your own visualizations for the media player Winamp using the Winamp SDK.
You could take a look at what kind of input parameters these plugins take in order to visualize something on screen.