This simple plugin was written to add classes to first, last, parent, even and odd elements of wp_page_menu and wp_nav_menu to support recognizing it in older browsers without :first-child, :last-child and :nth-child supporting.
Plugin adds the following classes to menu <li> tags:
“even-menu-item” to every even child of <ul> or <menu> tag, including first and/or last child.
Above classes are added separately to each menu level. Plugin use SimpleXML extension and requires PHP 5 or higher. Menu should have valid XHTML code.