Visual Beat - Interactive music video
Meludia - Listening exercises and to sharpen your ear and music theory skills
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.
GNU Solfege - GNU Solfege is free music education software.
SoundViz - Turn music and sounds into beautiful art
Perfect Ear - A simple yet advanced application for improving your solfege skills.