Songstack - Swipe to discover new music for Spotify
Figure - Propellerhead creates world-class software products and services that inspire music makers and provide the foundation for a worldwide creative musical community.
mixmello - mixmello is a free, open source tool to create remixed versions of your favourite playlists.
keezy - A colorful soundboard. Play with music.
Music Walker - Explore and play (via YouTube) songs similar to a seed song.
Splice - Music creation, collaboration, and sharing made simple.