ShareTube - Watch YouTube, synced with friends.
Partyhero - Pass your friends the aux!
Picaboo - Picaboo is a web-based image publishing and printing service that allows you to create personalized photo books, cards, and scrapbooks.
Join My Playlist - Listen to music live together with your friends in Spotify.
&chill - Watch YouTube & Twitch videos with people online
OutLoud Social Jukebox - Control the music with your friends in real-time