If you’re into trance, ambient, Goa, or any number of trippy kinds of music, RjDj is a must have app for your iPhone.

It actually generates music from the sounds it samples — in real time — from your iPhone’s mic (note, though, that is has to be the one on your headphones).  The various styles of music generation are grouped in "scenes" which you can choose depending upon your mood.

What’s really cool is you can record and play back the music you generate.

I recently put this on and walked around downtown Helsinki, having left a restaurant, walked across a public square, and down into a train station.  The result was a very trippy 10 minute recording that only gives you a glimpse of what it’s like to use this software.  It really is like being on a hallucinogen, walking around listening to the world filtered through its music.  Strange, tranquil, and at the same time, exciting.

One thing that is different between this and, say, LSD, is if you start to have a bad trip, you can turn RjDj off.

Here’s my recording:  Evening in Helsinki.mp3