I wanted to tell my readers about a great piece of software called
Unfortunately this is not free software
but it is now in my must have list so here is the scoop.
Nodal is a generative software application for composing music. It uses a novel method for the notation and playing of MIDI based music. This method is based around the concept of a user-defined graph. The graph consists of nodes (musical events) and edges (connections between events). You interactively define the graph, which is then traversed by any number of voices. These voices play the musical events as they encounter them on the graph. The time taken to travel from one node to another is based on the length of the edges that connect the nodes. Nodal allows you to create complex, changing sequences using just a few simple elements. Its unique visual representation shows a structural representation for generative systems that you can edit and interact with in real-time as the composition plays.
You can find it here. http://www.csse.monash.edu.au/~cema/nodal/