The main use that I have found is in setting a module as your Home Page and being able to pass it variables (example: NukeWrap). Under PHP-Nuke Administration, Modules, you can set your Home Page (The module, index.php is pointing to), but that doesn't allow variables to be passed to the module. NukeJump supports both PHP and JavaScript redirects to the module of your choice, or anywhere for that matter. The default is PHP.