Ability to open a song in Spotify or iTunes so you can add it to a playlist
This could be as simple as just tapping the album art twice. The first tap gives a hover state that says "open in Spotify" the second tap takes you to the song in the Spotify app.
This is currently possible if you’re not logged in to Spotify or Apple Music (just tap the “hear full song” button and you’ll see an option to open it in one of those apps). We plan to add a way to do this for logged in users very soon!