It'd be great if there was a music service that somehow incorporated the metadata in something like the Allmusic database. Say for example, while listening to an album, you could click on any side member and easily access any other album they'd played on. Same with songwriters, or album producers, recording engineers, etc. You can get all or most of this manually, but tied into a listening interface would be pretty slick.
That said, I don't know how much of a market there'd be for this
That said, I don't know how much of a market there'd be for this