Spotalike - Spotify playlist with similar songs, according to Last.fm
SubmitHub - SubmitHub makes it easy to contact music bloggers, Spotify playlisters, record labels and more. We give you all sorts of statistics and ways to filter who to send your music to.
MusaicFM - An iTunes like screen saver based on Spotify and Last.fm
Bowtie - Bowtie is a desktop accessory that allows you to see and control your music (iTunes, Spotify...
Spotify.me - Beautiful analytics on your Spotify listening habits 🎧
Magic Playlist - Get the playlist of your dreams based on a song