document.observe("dom:loaded", function() {
  $$(".submit_button input").each(function(i) {
    var original = i.readAttribute("value");
    i.observe("click", function(event) {
      i.writeAttribute("value", "Please wait...");
      i.disable();
      event.stop();
      i.up("form").submit();
    });
    Event.observe(window, "unload", function() {
      i.enable();
      i.writeAttribute("value", original);
    });
  });
});