Youtube-DJ - Mix YouTube songs together
Visualify - Visualize your top artists on Spotify
Pacemaker - Create and share mixtapes with friends
Spotify Web Visualizer - Beautiful full screen visuals for Spotify web player
djay Pro for iPad - djay Pro provides a complete toolkit for performing DJs.
Synesthesia - Synesthesia is a Spotify music visualizer that comes with the advanced support to listen to thousands of music tracks with the visuals side by side.