Axent.SelfLabeledInput is a prototype.js based class that changes your standard labels to the new web 2.0 like.
<form method="get" action="" id="after">
<fieldset>
<legend>Your Comment</legend>
<div class="input">
<label for="firstName">First Name</label><input type="text" id="firstName" name="firstName" />
</div>
<div class="input">
<label for="lastName">Last Name</label><input type="text" id="lastName" name="lastName" />
</div>
<div class="input">
<label for="eMail">E-mail</label><input type="text" id="eMail" name="eMail" />
</div>
<div class="input">
<label for="comments">Comments</label><textarea id="comments" name="comments"></textarea>
</div>
<div class="submit">
<input type="submit" value="Submit Your Comment" />
</div>
</fieldset>
</form>
<script type="text/javascript">
//<![CDATA[
new Axent.SelfLabeledInput('#after label');
//]]>
</script>