Aux is a social music app that works with Spotify to let you share music with friends. It lets you join rooms with your friends and share your favourite music, or help you find new favourites. You can think of it as a sort of social internet radio chatroom, of sorts.
Aux was born out of the desire to have a more social, organic way of finding new music, in addition to being able to hang out with friends. It's heavily inspired by Turntable.fm, a now-defunct site with a similar premise.
Aux is aiming to enter beta Spring 2017. Sign up for the waiting list here.