rateyourmusic.com's genre system works pretty well, it's based on user voting on genres for an album (genres are selected from a list, which is constantly being

rateyourmusic.com's genre system works pretty well, it's based on user voting on genres for an album (genres are selected from a list, which is constantly being updated by democratic process too) Here is their current genre tree: http://rateyourmusic.com/rgenre/ http://rateyourmusic.com/rgenre/ (caution, huge page) However, they don't have an API, so you would need to scrape web pages to get genres for your albums.