(function ($) {
    $.fn.Customers = function (interval, speed) {
        var loop = 0,
			list = $(this),
			height = parseInt($(this).find('li:first').css('height')),
			total = $(this).find('li').size();

        return this.each(function () {
            function repeat() {
                list.find('li:first').animate({ marginTop: "-" + (loop * height) + "px" }, speed);
                if (loop < total - 1)
                    loop++;
                else
                    loop = 0;
            }
            setInterval(repeat, interval);
        });
    }
})(jQuery);