This page has some Javascript which counts the number of forms in the page.
<script>
var f = document.forms;
for(var i = 0 ; i < f.length ; ++i) {
sleep 1;
f[i].elements[0].value="This is form "+i;
document.writeln("found form "+i+"<br>");
}
f[1].radiotest[1].checked=true;
</script>