This site by Rory Byrne and Rian Dillon is an amazing use of Spotify's API:
It connects to users' Spotify accounts and tracks plays to show live plays and track top songs, artists, and albums from the community within the past 7 days.
I linked specifically to the hip hop feed of Metro which creators invited Reddit r/hiphopheads users to join, but the site has other feeds and also integrates with services beyond just Spotify via Chome extension.
It's a very cool idea and I'm a huge fan of not retaining more user data than needed.
Check it out and follow their Medium page for updates.