The Music Room
A 3D world, filled with music coming from different sources, blended together in surround sound (5.1/7.1). Similar music is closer together (for example, based on last.fm information). You can freely move around, with distant sources fading out, until you only hear the closest source (standing “inside” it).
Think of different rooms for different musical styles, or a way to zoom in and out on a globe of all the music on your hard drive, visualized using Milkdrop, or band pictures and videos associated to the songs. I can also imagine to follow the history of a certain musical style by walking through a corridor (from Blues to Classic Rock to Stoner Rock?).
Possible proximity criteria: City of origin, age, musical similarity, etc.. It should be possible to navigate through representative songs of a decade, or a single band’s history. The possibilities are endless.