Maybe this isn't exactly what you were thinking but I wanted to get some social listening features added to Spotify as well so I built JQBX: https://www.jqbx.fm .
this reminds me of Fliptape, a project I built many moons ago. Looks great and is basically what our roadmap was. We went mobile first back in 2011 with the same concept. Would love to have kept it going.
Fingers crossed history doesn't repeat itself w/ 3rd party apps build on Spotify. If you have any feedback or ideas that have been simmering please hit me up (email is at the bottom of the website).
Maybe it'll scratch your itch, figured I'd share.