The Now Playing overlay is designed to be as pretty and functional as possible, it has had contributions from professional graphic designers.
This overlay can be used to show your stream what you are listening to. This works with any service that has a lastFM integration. Users who are Pixel-Pro members are also able to link their Spotify account to get direct Spotify integration, bypassing the need for LastFM.
The overlay also displays any new song when you start listening to it.