Here's a menu navigation use case that I run into all the time:

"A click on a top level item in a menu should redirect to it's first child."

For example, if this is Primary Links:<br>About<br>-Overview<br>-History<br>-Contact<br>Products<br>-Beef<br>-Chicken<br>-Statuary<br>

Then if I click on About I should be taken to the Overview page.

This is possible in Drupal 6 - you can create two menu links that point to the same node. If you create one of the menu links via the node edit form, D6 will even remember which one it is (Drupal 5 would get confused).

What's difficult is specifying which menu item should have the active trail once you make it to the Overview page. Usually you want the child "Overview" menu item to be active, and not the parent "About" menu item. However, there's no way to specify this in D6 - Drupal will set the menu item with the lowest id number to be the active trail.

You can't work around this problem with URL Aliases. Drupal is too smart for you, it seems to dereference the multiple aliases, and behavior is the same.

I was trying to solve the problem for the tenth time two weeks ago, when I discovered the path_redirect module - which almost does the right thing! You can create new paths - not aliases - that redirect to the same node. Unfortunately you cannot add path_redirects to the menu system.

There's an open issue requesting menu functionality and as of May 11th there's a work around by sbandyopadhyay that allows you to put path_redirects into the menu system.

However, the maintainers of path_redirect are skeptical that this feature should be added. I think that, for the use case described here, they are probably right. It would be better to have a simpler UI. Maybe something similar to - or an extension to - nodesymlinks that would let you create multiple menu links for a path and specify which is "canonical".