nicknicknick,
<head>
<title></title>
<meta charset="utf-8" />
<style type="text/css">
.replies {
display: none;
}
</style>
<script type="text/javascript">
function show_hide_thread_replies(id){
var el = document.getElementById(id);
el.style.display = (el.style.display != "block") ? "block" : "none";
}
</script>
</head>
<body>
<div id="thread_113">
<!-- куча html кода -->
<div class="replies" id="replies_113">123
<!-- куча html кода -->
</div>
<a onclick="show_hide_thread_replies('replies_113')">Скрыть/показать</a>
</div>
<div id="thread_116">
<!-- куча html кода -->
<div class="replies" id="replies_116">456
<!-- куча html кода -->
</div>
<a onclick="show_hide_thread_replies('replies_116')">Скрыть/показать</a>
</div>
</body>
</html>