Gnoosic - Even if you don't know what you are looking for - gnod will find it.
22tracks - DJ curated Spotify playlists on iOS
Musicroamer - A visual Pandora for discovering new music
Spotify - Map shows when two people play same song at same time
TasteDive - TasteDive recommends similar music (musicians, bands), movies, TV shows, books, authors and games, based on what you like.
Yeloha - Airbnb for solar power