Spotify - Map shows when two people play same song at same time
EarMaster - Professional software for ear training and practical music theory on Windows and Mac.
SoundCloud - Enjoy music & follow favourite artists
GNU Solfege - GNU Solfege is free music education software.
Last.fm - The world's largest online music service. Listen online, find out more about your favourite artists, and get music recommendations, only at Last.fm
Perfect Ear - A simple yet advanced application for improving your solfege skills.