Some of these could turn out to be interesting for describing licensed content on the web, all rather interesting.

hAudio proposed microformat.

Proposed hAudio to RDFa mapping.

RDFa-deployed Multimedia Medata (ramm.x) may be an effort to map and standardize use of existing and upcoming media description standards in RDFa ... I had to skim "ramm.x in 10 sec" and "what ramm.x is NOT" a few times to gather that, but the key description on that page seems to be:

Does ramm.x replace RDF-based multimedia vocabularies, as, e.g., the Music Ontology Specification? No! ramm.x aims at bringing existing formats, as MPEG-7 and the like, into the Semantic Web. It acts as a bridge using a certain formalisation of an existing vocabulary.

Getting a bit more esoteric, Protocol for Web Description Resources (POWDER):

facilitates the publication of descriptions of multiple resources such as all those available from a Web site.

Which is a bit of an understatement.