function showSsnField() {
    $("ssn_p").style.display = "block";
}

function hideSsnField() {
    $("ssn_p").style.display = "none";
}

function updateAddressField() {
    new Ajax.Updater('address_p', '/signup/address_list?ssn=' + $("ssn_field").value);
    $("address_p").style.display = "block";
}