Songstack - Swipe to discover new music for Spotify
Shared Spotify - Find the common songs you have between friends
BandNext - Discover bands that sound similar to artists you already love with BandNext. A single click saves your results to a Youtube playlist.
Playlist Souffle - Swap Spotify playlist tracks based on album or artist
22tracks - DJ curated Spotify playlists on iOS
Songlink - Share music with anyone.