In the process of setting permissions on a subsite and it's children, I noticed it would be an easier process if there was a link back to the parent. My OpenACS snap-shot (Oct 2002) only has links to the children. After processing a few permissions, navigating back to the parent would require numerous clicks on the browser's <back> button.
I agree that this would be very helpful. I know there's been discussion about improving the permissions UI, but I'd suggest logging this in the bugtracker in the meantime.