If you have already used them you know that to launch your ZF application you need to add these lines to your application.ini

bootstrap.path = APPLICATION_PATH "/Bootstrap.php"
bootstrap.class = "Bootstrap"

and create the file boostrapp.php with the following code

<?php
class Bootstrap extends Zend_Application_Bootstrap_Bootstrap
{
}

This is the best boostrapp that you can have, without any method. You can obtain this moving all your methods on the resources.
But if I have an empty class why should I create this file?

There is a little tip to remove this file from execution of your scripts, you have to change the previous lines of your application.ini with these

bootstrap.path = APPLICATION_PATH "/../library/Zend/Application/Bootstrap/Bootstrap.php"
bootstrap.class = "Zend_Application_Bootstrap_Bootstrap"

public function indexAction()
{
  $this->_helper->layout()->disableLayout();
  $this->_helper->viewRenderer->setNoRender(true);
}

If you want switch off them for all actions of controller put these lines into preDispatch() method:

public function preDispatch()
{
  $this->_helper->layout()->disableLayout();
  $this->_helper->viewRenderer->setNoRender(true);
}