Keys and callback URI are given with your personal Spotify developer account, register here: Spotify Developer.
SpotifyCoverFlow is a simple script to display a full-screen & high resolution image of your current playing (or most recent) song on Spotify. The intended use is to dedicate a RaspberryPi (or similar device) and a monitor/screen to be an always on digital poster for your favorite music artwork.
At the time of writing this script, Spotify only supports image artwork up to 640x640. To counteract this - the current song is then searched through iTunes to grab artwork up to 10000x10000. If the artwork can't be found on iTunes, the lower resolution Spotify artwork will be displayed.