I'm sure I'm missing something here.

I need to have some of my live pages NOT in the navigation menus, but still accessible by URL.

Please, a simple answer.

Thanks.

For a live page that you do not wish to appear in the navigation menus, under Admin Functions > Edit Site Pages, click on Edit Link for that page, and uncheck "Active."

The page will still be accessible to you. To view it, under Admin Functions > Edit Site Pages, scroll down to the page. Then click on Edit Page to see the page contents.

To make the page reappear in the navigation menu, recheck "Active" under Edit Link.

While you're viewing the Edit Link using edit site pages, and turning off the Active box, you might also want to unclick the Restricted box if you want people to be able to see that page without logging in - and then click on the "Open Page Info..." link to display the URL for that page which you could post elsewhere or email to anyone you want to view that page.