Not only can you make your own playlists on Spotify, you can also make joint playlists with friends. Simply make a playlist, right- or control-click on it and select “Collaborative Playlist.” Then select “Copy HTTP Link” and you’re ready to go: every Spotify user you send that link to will be able to edit and add to the playlist. By the time your party comes around, “SUMMER OF KEITH 2012” will be ready for the big-time — but please, no Don’t Stop Believin’. I think we’ve all heard that song a few too many times.