Context Free - Fractal generator
Context free is a free fractal generator program which can produce some very interesting effects - I am certain that many of these could be used for mapping purposes, eg. making minor road networks.
The downside is that the interface works on the 'you need to be a programmer' level - which I'm not. I'm still struggling to understand it.
Perhaps someone more programming literate can make something out of it? I was particularly interested in the 'underground map' images you can generate with it.
You can find it here: http://www.contextfreeart.org/