RjDj Album is one of the most interesting music apps available for the iPhone. Instead of other apps offering you different music to listen to, RjDj helps you create music based on your environment. All you need to do is plug in your headphones, select a track, and let your environment and RjDj do the rest.
There are two versions of RjDj: Album and Single. Album offers you six different tracks (Eargasm, Echolon, Gridwalker, Loopinger, Noia, and WorldQuantizer). Single on the other hand only offers you one track (Echolon). Considering how unique and new this concept is, it's definitely understandable that people will want to try the app out first before purchasing it.
Depending on the track and the sounds around you, the music that RjDj makes could be the most interesting or the most boring thing you've heard. Try talking into the mic or putting it next to objects that make weird sounds, like fans. Even better, use it as you walk down a busy street, you'll get a great feel for it that way.
With RjDj you can record the tracks, but unfortunately unless you have a cord to hook it up to your computer, you're stuck with the music just on your iPhone. This app is excellent and is something that everyone with an iPhone should have, considering how every environment will create a unique listening experience for you to enjoy.