$(function() {
                    // set opacity to nill on page load
                    $("ul#menu span").css("opacity","0");
                    // on mouse over
                    $("ul#menu span").hover(function () {
                            // animate opacity to full
                            $(this).stop().animate({
                                    opacity: 1
                            }, "slow");
                    },
                    // on mouse out
                    function () {
                            // animate opacity to nill
                            $(this).stop().animate({
                                    opacity: 0
                            }, "slow");
                    });
            });