RjDj is a music application for the Iphone, that, according to the developer, is a type of digital drug:
It uses sensory input to generate and control music you are listening to. RjDj is mainly consumed with headphones. Think of it as the next generation of walkman or mp3 player. The consumer experience of RjDj is similar to the effects of drugs. Drugs affect our sensory perception, so does RjDj. RjDj is a mind twisting hearing sensation.
I’m not sure about the “digital drug” angle, but RjDj is an interesting application/interactive artwork that looks like it could actually develop into a platform for creating interactive iPhone music experiences.
RjDj is using PD (Pure Data) to create RjDj “scenes”. PD is an open source software and you can find all necessary information on the Pure Data site.
RjDj is currently in private beta, but they hope to have it in the iTunes App Store soon.