Ever heard of the music site plug.dj?
For a long time ago I was introduced to a social music site called plug.dj by a friend of mine and it was love on first sight.
The concept is simple. You join a DJ queue and suggest YouTube videos or songs from SoundCloud, chat with other users or just enjoy the music. The site has a very nice and polished user interface and the rating system makes it truly awesome. Users can like, dislike and save songs to favorites which makes it great for discovering new music.
The site was closed late September 2015, but relaunched in the end of July this year. They even kept all the user data and playlists!