If you put all the local forums in one category, you can link to only that category somewhere by using
http://www.yourhost.com/forum/ubbthreads.php?Cat=5 if 5 is the number of that category. The Category won't be listed at all on the main index, as if they don't have access to it.
Where you put this link is up to you, if you want it to show up on the main index you just edit templates/default/ubbthreads.tmpl
To hae the category show up on the main index but without the forums would be trickier, but I guess it is possible.
