<!-- DIV per Klick einblenden und ausblenden -->

<script>
function show(id) {
    if(document.getElementById) {
        var mydiv = document.getElementById(id);
        mydiv.style.display = (mydiv.style.display=='block'?'none':'block');
    }
}
</script>
<a href="" onclick="javascript:show('divText'); return false">
Einblenden / Ausblenden</a>
<div style="display: none" id="divText">Text</div>