On the A9 Developer weblog there is an article today on he SiteInfo feature that was until now only available when you used the A9 Toolbar. They now have developed a Firefox extension that will give you the same functionality. Normally the siteinfo tab gives you the Alexa information about a site: traffic ranking, reviews, etc., and it presents you with a short “people that visit this site also visit …” list of sites. However if you go to IBM.com or Amazon.com you will see that this tab changes into a site navigation menu. The posting on the A9 weblog today and an earlier posting in September give some other examples.
You can control this through the generation of a sitinfo.xml file, to be placed in the root directory of your website. The details of the file format are in the SiteInfo Spec. I added a template to my moveable type installation that automatically generates this with a menu for the last postings, categories, etc.
My moveable type template for this can be downloaded from here. Set it up as a new template to generate a file siteinfo.xml on rebuild.