Eclps is a concept of a music player that is based on the idea of a natural interface based on gestures and actions that we are accustomed to while interacting with mobile devices.
The basic principle was to remove as many GUI elements as possible while retaining the core functionality of a mobile music player, so instead of having an icon that you'd need to tap to enable "repeat" you'd draw a circle on the screen. You'd advance and go back in lists by swiping right and left, shake your device to enable shuffling of songs or pinch to change volume.
This is only a concept though and the main disadvantage of a player like this would be the steep learning curve when it comes to using the interface. This is not meant as a functional product though, but more a case study by someone who doesn't have experience in designing interfaces.