Spotify.me - Beautiful analytics on your Spotify listening habits 🎧
BeatSense - Discover great music hand-picked by real people, in a single click. FREE and in real-time!
Magic Playlist - Get the playlist of your dreams based on a song
20v - Create a custom music channel based on a single song
SpotMenu - Spotify and iTunes in your macOS menu bar
The Midi Shrine - A collection of MIDI files for SNES, NES, GameCube, Game Boy, and others.