NOISESUPPLY - Pandora for SoundCloud
22tracks - DJ curated Spotify playlists on iOS
Move to Apple Music - Convert your Spotify playlists for Apple Music
BandNext - Discover bands that sound similar to artists you already love with BandNext. A single click saves your results to a Youtube playlist.
Tune My Music - Transfer Playlists Between Music Services
Spotify - Map shows when two people play same song at same time