Check out this incredible piece of music. I was very impressed. It is a fine example of algorithmic music/generative music; music which is not explicitly written by a composer, but rather is created through some sort of computational process.
This particular piece is based on a generalized form of the Fibonacci series. (The fibonacci series is strongly related to nature, and is often incorporated into art)
As it happens, this piece of music is not
purely algorithmic. The actual score was generated, but the piece was ultimately arranged by a human ear. Regardless, it is still wonderfully impressive.
The link provides a very insightful essay, along with a place to download the track.
http://www.it.rit.edu/~jab/Fibo98/