ShareTube - Watch YouTube, synced with friends.
Heartbeat - Listen to music with your friends together, on Spotify
Showgoers - Showgoers is a website dedicated to watching Netflix movies together with friends or loved ones who are not sitting on the same PC.
Liyo - Stream your favorite music live with friends 🎶
Netflix Party - Netflix Party is an extension for watching Netflix remotely with friends and family for movies nights with that long-distance special someone.
Parallel - Listen to music with friends over Spotify at the same time