Playlist Machinery - Tools that help you create & organize your Spotify playlists
Spotalike - Spotify playlist with similar songs, according to Last.fm
Playlistor - Convert Apple Music playlists to Spotify and vice versa
MusaicFM - An iTunes like screen saver based on Spotify and Last.fm
FreeYourMusic - Migrate from and to any music services
Bowtie - Bowtie is a desktop accessory that allows you to see and control your music (iTunes, Spotify...