I am currently creating an extranet site in MOSS 2007 with lots of
security needs. One of them is a custom, top navigation menu display
as individual graphics that each link to an specific page on the site.
I have need to 'security trim' each option based on the SharePoint
Group that the user has defined. These groups are custom and not
provided by SharePoint out-of-the-box. There is a group for each menu
option as well as an 'all' group. For example, we have:

TabA, TabB, TabC

If I'm logged on to the site and have TabA and TabC groups assigned to
me, then I can't see TabB. If I'm logged on to the site with AllTabs
assigned, then I can see all three tabs. If I have only TabC, then I
only see TabC.

Right now, I have the security assigned at the page level so if a user
without those permissions clicks on a tab, then they get the security
error and the page is not displayed. What I would like to have is to
not display the tab at all by checking which groups are assigned to
the user and only displaying the tabs they have permission to see.

My preference is to do this as a feature or directly in the master page.

Any help is MUCH appreciated as always.