With SpotiStats you can know which are your favorite artists of the moment your favorite musics as well as manage your playlists!
With this application you'll be able to find out who your favourite artists have been for the last month the last 6 months or since you've had Spotify. You'll be able to do the same with your favourite music!
You can also easily edit your playlists with the Playlist Manager and find out if there's any duplicate music in your playlists.