<textarea id="input_26" class="form-textarea" name="q26_26" cols="60" rows="3"></textarea><input onclick="InpPrew()" type="button" value="Посмотреть">
<div id=preview ></div>
<script type="text/javascript">
function InpPrew(){
document.getElementById('preview').innerHTML=document.getElementById('input_26').value;
}
</script>