Find out how much a playlist you made has in common with another playlist
You can get your spotify playlists as csv's here http://www.playlist-converter.net/#/
Then you can use this code to compare them, generating some text stats and 4 venn diagrams. Simply run the python code and select the two csvs that have the playlists you want to compare. Technically speaking you could compare all kinds of different things with minor tweaking.