I just committed a YAML discography schema proposal over on github. This came about as a potential method to import/export discography information for Pushtape. Existing music schemas tend to be either too specific to their implementation, too general for discography use, or too difficult to implement. 
I think it'd be useful to have a portable discography file format that can be read/written by both machines and humans.
It could be used to import/export discographies for open web apps like Pushtape and Cash Music, it could be used as a resource to manage a Jekyll powered music site, it could be read by music players, used as an API response for a music website, or quickly converted to other file formats. Since it is just YAML, it can be edited by hand or by machine. If you think such a format would be useful for you or have ideas for how it could be improved (what I've put up is just an initial draft), feel free to contact me or submit a pull request on Github.
 Existing Music Schemas for the web