I launched volt.fm in early March and today it reached 50k users.
With volt.fm you get a cool public page for your Spotify profile that shows your stats (top artists/songs/genres), playlists, and even the song that you're currently listening to.
See an example here → volt.fm/chrismessina (yes, that's Chris Messina!)
It also lets you browse artists, genres, and songs to discover new music and find people with similar tastes.
My next plan is to add a feature that lets users share music with their friends and get human non-algorithmic recommendations from them.