Based on ?superfish? type CSS menus (see link), this class allows dynamic generation of CSS and HTML to produce horizantal menus at runtime.
This does not actually product Superfish functionality, but the code should be compatible with adding Superfish.
It is advisable to cache the menu if possible, as there is considerable overhead to running this every time the script is accessed and on a busy site with many buttons and layers could have a significant detrimental effect on performance. Simple example adding a three button menu where second button has a sub-button:

$hmenu = new HMenu;
$hmenu->addButton('Home', '/');
$hmenu->addButton('Products' '');
$parentid = $hmenu->getLastID();
$hmenu->addButton('Product One', '/prod1/', 'Product One', 2, $parentid);
$hmenu->addButton('Product Two', '/prod2/', 'Product Two', 2, $parentid);
$hmenu->addButton('Contact Us', '/contact/');

// then use...
// $hmenu->generateCSS() at the end of your  section
// and $hmenu->generateHTML() where the menu would go