Footer menus aren’t as popular as they used to be, but still used often for SEO. You may not want to include the entire menu on the footer, maybe just a section or a subcategory. Here is one way of doing that.
function mymodule_mainmenu_subnav($link_name) {
$links = array();
$menu_tree = menu_tree_all_data('main-menu'); // grab main-menu items
foreach ($menu_tree as $item_name => $item) { // loop through all menu items
if (strpos($item_name, $link_name) !== FALSE) { // if $link_name is found in $item_name
foreach ($item['below'] as $sub_item) { // loop through all 'below' items
$links[] = l($sub_item['link']['link_title'], $sub_item['link']['link_path']);
}
return theme('item_list', array('items' => $links)); // return list of links
}
}
}
Good Luck!