The social cataloging site Rate Your Music has a very in-depth genre tagging system. For each album and track, users debate and vote on which primary genres and secondary genres apply. For example Radiohead's OK Computer has Alternative Rock and Art Rock primary genres and a highly controversial Space Rock Revival secondary.
Each genre has a lineage of parent genres so each release tagged with a genre must also be a part of each parent genre. For example: Electronic > Electronic Dance Music > House > Tribal House. Also: Rock > Metal > Thrash Metal > Technical Thrash Metal.
There's a queue for submitting proposals for new genres and modifying the definitions of existing ones. There's also a complex chart system for filtering releases by genres, types, and descriptors. I think I last heard there were ~1300 music genres on the site.
Each genre has a lineage of parent genres so each release tagged with a genre must also be a part of each parent genre. For example: Electronic > Electronic Dance Music > House > Tribal House. Also: Rock > Metal > Thrash Metal > Technical Thrash Metal.
There's a queue for submitting proposals for new genres and modifying the definitions of existing ones. There's also a complex chart system for filtering releases by genres, types, and descriptors. I think I last heard there were ~1300 music genres on the site.