Firesong - Giphy for Music in Slack w/ Emoji Search
Slack Meme Bot - Spice up your team conversations with memes
GoGifApp - Free Slack GIFs App, multiple images to pick from at once
My Slack Emoji - Turn your team photos into Slack emoji's
VixT on Slack - The best video mashup app now on Slack.
Slackbox - Spotify playlist collaboration through Slack