Moved to ClientSide Technologies.
I don't know if there's a general term for what you're wanting, but I know that it'd be simple to do with a bit of Javascript. You could go about it several different ways, mostly depending upon how you want to identify which form elements are to be toggled on and off. Here's a simple example:
<html>
<head>
<script type="text/javascript">
var controlIDs = new Array("test1", "test2");
function hideControls(hide) {
for(i in controlIDs)
document.getElementById(controlIDs[i]).style.visibility = (hide ? "hidden" : "visible");
}
</script>
</head>
<body>
<form method="GET" name="foobar">
<div>Hide: <input type="checkbox" name="hideCtrls" onclick="hideControls(this.checked)"></div>
<div>Test1: <input type="text" id="test1"></div>
<div>Test2: <input type="text" id="test2"></div>
</form>
</body>
</html>
(And yes, I know it's not a valid HTML document. :p)