EchoNest (http://the.echonest.com/) provides at least 'genre' information about music. Your question could useEchoNest is not 100% 'open', but per their 'ground rules': 'terms of service allow for most reasonable non-commercial uses' (developer.echonest.com/docs/v4#ground-rules).
You can get a bit more contextrate-limited API key for free, thoughrequiring only attribution. So depending on the project, it might be a good fit, or at least a starting point.