[apfeifer]

You could insert it in the bottom of all the forums like they do here at vbulletin.org linking back to vbulletin.com, or you could put a little thing like

PHP Code:

if ($forumid == "X") {
    $var .= "what you want the link to be";
} 


That would insert that info after forum X. You would want to make it have all the html/etc though, and maybe even put it in a custom template.