// Courtesy of http://www.456bereastreet.com/archive/201011/removing_title_attributes_from_wordpress_links/
function remove_title_attributes($input) {
return preg_replace('/\s*title\s*=\s*(["\']).*?\1/', '', $input);
}
add_filter( 'wp_list_categories', 'remove_title_attributes' );
add_filter( 'wp_nav_menu', 'remove_title_attributes' );