I wrote an interface to graphviz in PHP that takes a pipe delimitted file and converts it to a site map. Sample files to look at:

* tab delimmited file -- the file you upload with your node list
* dot file -- the dot file the script creates for graphviz
* demo diagram -- the dot output as a gif with image map

Going to work a bit at adding more options, e.g. ability to select shape and line colors, font size, and page size.