Активный пункт меню при прокрутке

// Cache selectors
var lastId,
    topMenu = $("#your selector"), // here class or id your menu
    topMenuHeight = topMenu.outerHeight()+100,
// All list items
    menuItems = topMenu.find("a"),
// Anchors corresponding to menu items
    scrollItems = menuItems.map(function(){
        var item = $($(this).attr("href"));
        if (item.length) { return item; }
    });

// Bind click handler to menu items
// so we can get a fancy scroll animation
menuItems.click(function(e){
    var href = $(this).attr("href"),
        offsetTop = href === "#" ? 0 : $(href).offset().top - 100;
    $('html, body').stop().animate({
        scrollTop: offsetTop
    }, 1000);
    e.preventDefault();
});

// Bind to scroll
$(window).scroll(function(){
    // Get container scroll position
    var fromTop = $(this).scrollTop()+topMenuHeight;

    // Get id of current scroll item
    var cur = scrollItems.map(function(){
        if ($(this).offset().top < fromTop)
            return this;
    });
    // Get the id of the current element
    cur = cur[cur.length-1];
    var id = cur && cur.length ? cur[0].id : "";

    if (lastId !== id) {
        lastId = id;
        // Set/remove active class
        menuItems
            .parent().removeClass("your active class")
            .end().filter("[href=#"+id+"]").parent().addClass("your active class");
    }
});