[рони]

SLameN,

<script>
        $(document).ready(function(){
            var links = $('#nav > ul > li >a'), link = links.eq(0), locHref = location.href;
            links.each(function () {
                if(locHref.indexOf($(this).attr('href'))!=-1){
                    link = $(this);
                }
            });
            link.addClass('nav_active');
        });
</script>