Here is an example of how to get a value from a nested form in an iframe. It works in IE6, but not Netscape 7.1.
PageOne.htm
<html>
<head>
<script language='JavaScript'>
function Search() {
alert(document.frames("PageTwo").document.forms("Members").elements("Search").value);
}
</script>
</head>
<body>
<input type='button' value='Search' onclick='Search();'>
<iframe name='PageTwo' src="PageTwo.htm" width='100%' height='100'>
</body>
</html>
PageTwo.htm
<html>
<body>
<form name='Members'>
<input type='text' name='Search' value='Chris'>
</form>
</body>
</html>