Shared Spotify - Find the common songs you have between friends
Jukebot - Turn Slack into your team's very own Spotify jukebox
Spotify Codes - Share codes for songs, artists, and playlists from Spotify
Daily Fire - A Slack app for every music lover
Bands on a Budget - Economical SWAG meant for bands, often hijacked by startups
Heartbeat - Listen to music with your friends together, on Spotify