"TouchGraph provides a hands-on way to visualize networks of interrelated information."
Go. Play. Now.
This is an awesome tool for checking the "entrenchment" of a given site. I recommend setting Radius to "ALL" for the primary URL. Now that's a site map. Double-click any other node and watch the next level of relations explode. Hit Clear to start over with a new site.
There is also a downloadable Touchgraph Wiki-browser.