<script>
function showSomething() {
var a = $('.first-link-class');
a[a.hasClass('handle') ? 'removeClass' : 'addClass']('handle')
}
</script>
<a href="#" onclick="showSomething();return false;" class="first-link-class">Показать</a>
<a style="display: block; width: 140px; height: 35px; text-indent: -99999px; background: url("images/top.png") no-repeat scroll 0% 0% transparent; outline: medium none; position: absolute; z-index: 995; bottom: 0px; right: 108px; top: -35px;" class="handle" href="#" onclick="showSomething();return false;"></a>