First it was Sony Walkman, replaced by mp3 players such as Apple iPod. Both devices created a new way of listening to music and were duplicated by numerous companies in thousands of models. It is hard to imagine what will displace the current wave of mp3 players. They increase their capacity every few months, their sound quality is very good and since many of them have no moving parts they are very reliable. Personal music never sounded that great nor was it so easy to manage. So what innovation will replace them and how long will it take?