It looks back through all the playlists you've created, finds overlapping tracks, orders them by occurrence and pushes the top 30 into a new "Top Spot" playlist!
Quick tour: https://www.youtube.com/watch?v=od42DRQghfA
Example playlist: https://open.spotify.com/user/1191879751/playlist/41SpRrw97X...
I also recorded the whole sad sorry development as a screencast, which I'll be splitting up into a dozen or so videos (with post-production commentary to provide context) and posting to YouTube so people can see the very messy, copy/pasting flow of creating a React web app in just over 4 hours.
Hit me up with any other comments: http://twitter.com/ben_howdle