LiveTrax - LiveTrax is an app by MasterMedia Productions through which musicians can control the playback of their favorite track during live performances by using simple controls.
Spotify - Map shows when two people play same song at same time
Go Button - Go Button is a mobile audio app designed to provide professional playback of music and sound effects for live shows. It provides a creative, self-contained show control system that runs on your iPad, iPhone, or iPod touch.
SoundCloud - Enjoy music & follow favourite artists
TrueFire - The Best Guitar Lessons Online Fast. Easy. Fun.
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