I recently came on this thread, and Jason's work is phenomenal. I found a number of opportunities for improvement and put those into a fork of his original project. (Thanks for making it open source, Jason!) This one does a lot, including applying a template to your file (so it's pretty), and adding the full page text so you can search the diagram for page text.
You can download the binary on my site:
http://nik.me/crappysoftware
Or get the source on GitHub:
https://github.com/nikjft/Omnigraffle-Sitemap-Generator