ShareTube - Watch YouTube, synced with friends.
Slackbox - Spotify playlist collaboration through Slack
Showgoers - Showgoers is a website dedicated to watching Netflix movies together with friends or loved ones who are not sitting on the same PC.
Brain.fm - Music designed for the brain to enhance focus, relaxation, meditation, naps and sleep within 10 - 15 minutes of use.
Netflix Party - Netflix Party is an extension for watching Netflix remotely with friends and family for movies nights with that long-distance special someone.
Radionewify - Only music you've never listened to before