How to: Install Spotify in Ubuntu
http://haxordoubt.blogspot.com/2013/04/how-to-install-spotify-in-ubuntu.html
Spotify is a great way to listen to music by streaming it on your phone, in your browser, or on your Linux desktop. You can stream everything, upgrade and sync tracks and playlists offline, or purchase individual tracks to keep forever.
The following code will add the Spotify repository, authenticate it (which makes sure the software you install is the official one), checks for the latest version, and installs Spotify. You should copy and paste this code into your Terminal and execute it.
You can view these commands individually at the Official Spotify Linux Preview page.