You may be aware about augmented reality or not. In entertainment and on mobile devices this feature displays additional information by turning a cam, a webcam or mobile cam, on an object to fetch information mostly located at the internet to be displayed on the screen and which even may be interactive. Now the spanish agency Musikame has put such information on a cd cover enabling to interact with content. By turning the cam onto the cd cover one is able to use a sound machine and to scratch and perform other tasks. This might be a bit complicated, especially if you are not aware about augmented reality. So have a look at the videos within the following article: Augmented Reality CDs into DJ Tools; DJing with SoundCloud, Clock Faces, More.
Similar services are available at online music software.