Did you missed the Guest access level in Joomla 1.7?
After struggling for years to set up menu items shown only for guest visitors in various Joomla/Mambo versions prior Joomla 1.7, was a real relief to have an easy and foolproof way to do it. No hacks needed, no scripts to add, no configuration trickery... you simply selected from the Access Level dialog the Guest access group for anything qualifying for this settings (modules for example, but not only..) and you where set! And if you upgraded your site from Joomla 1.7 to Joomla 2.5 the feature where still there. Recently I had a big surprise, I needed the feature in a brand new Joomla 2.5 site... and don't found it!!