RightGIF - Less noise, better GIFs. A better /giphy for Slack.
Magic Playlist - Get the playlist of your dreams based on a song
Yarn for Slack - Drop TV and movie clips into your Slack chats
Spotalike - Spotify playlist with similar songs, according to Last.fm
Firesong - Giphy for Music in Slack w/ Emoji Search
Playlist Machinery - Tools that help you create & organize your Spotify playlists