Hyperbeam - A better way to watch together online
Metastream - Watch streaming media with friends
Watch2Gether - Watch2Gether is an app that allows multiple people to watch the same content simultaneously and interact with each other while watching.
Showgoers - Showgoers is a website dedicated to watching Netflix movies together with friends or loved ones who are not sitting on the same PC.
StreamParty - StreamParty is a watch communiry, that allows you to watch video streams in sync with the people you care about, on multiple services.
Jelly Party - Watch anything together.