After playing with other graph layout utilities (yEd, linlog) I’m back to using the Mac port of Graphviz. This image links to a PDF:
I printed out a dot file by changing a few lines from the demos of the Metaweb javascript template, then fed this into Graphviz. A 3 ft x 4.5 ft poster of this would be around $30.
Some of the new people:
Mike Love's blog 
You added Karel Capek. He’s the bestest.
How does it look if you run it through neato -Gmodel=subset?
How fast is that?
Hi Mike, just came across this Hyperbolic Browser Javascript library. That might make a cool interactive view of your graph.
Stephen: I’m installing graphviz so i can try neato.
Will: Hi! Yeah – i wonder if it has to be a proper tree though. I’ve got a lot of backrouting.