Magic Playlist - Get the playlist of your dreams based on a song
Spotalike - Spotify playlist with similar songs, according to Last.fm
SpotMenu - Spotify and iTunes in your macOS menu bar
Playlist Machinery - Tools that help you create & organize your Spotify playlists
Spotify - Map shows when two people play same song at same time
Your 2017 Wrapped by Spotify - Relive all the music you discovered and loved in 2017.