but the structure above isn't dynamic enough.

What if you have this kind of situation:

<script language="JavaScript">

function sendVar(val){
document.form.pob1.value = val;

function show(id)
{
if (document.getElementById(id).style.display == 'none')
{
document.getElementById(id).style.display = '';
}
}

function hide(id)
{
document.getElementById(id).style.display = 'none';

}
}
</script>

In JSP

<table id="0">
<html:select name=country onchange="show('1'),hide('2');"/>
</table>

<table id="1" style="display:none;">
<html:select name="pob" onchange="setVar(this.value);"/>
</table>

<table id="2" style="display:none;">
<html:select name="pob" onchange="setVar(this.value);"/>
</table>

<input type="hidden" name="pob1" value="">

But, eventually Javascript didn't send the value to hidden name=pob1

I'm out of idea..

hehe..