Music streaming services can be frustrating if you're an avid listener, since your definitions may not line up with theirs. They may lump trance, techno and drum-and-bass into a generic "dance" category, for instance. Spotify, at least, knows it needs to do better... and it's asking you for help. It quietly launched a Line-In feature that lets you suggest edits to the metadata for artists, albums and songs. You can recommend genres, tags, moods and even nicknames. You could clarify that an "electronica" album is really tech house, or remind Spotify that many people refer to Metallica's self-titled record as "the Black Album."