Songstack - Swipe to discover new music for Spotify
Music Walker - Explore and play (via YouTube) songs similar to a seed song.
stats.fm - With the click of a button you'll be logged with your Spotify account and you'll instantly gain access to a valhalla of cool stats and insights.
remixmonsta - Tired of Despacito? Find a cool remix instead
Remix - Solidity IDE (Integrated Development Environment)
Musicroamer - A visual Pandora for discovering new music