Pass URL to menu item call back
You can use page arguments:

function MYMODULE_menu() {
  $items['foo'] = array(
    'title' =&gt; 'Bar',
    'access arguments' =&gt; array('access content'),
    'page callback' =&gt; 'MYMODULE_baz',
    'page arguments' =&gt; array('http://google.com', 'another arg'),
  );

  return $items;
}

function MYMODULE_baz($url, $another_arg) {
  // Do something with $url, e.g. redirect.
  drupal_goto($url);
}


That's quite a contrived example, if you are redirecting, you could shorten that by just using drupal_goto as the callback:

function MYMODULE_menu() {
  $items['foo'] = array(
    'title' =&gt; 'Bar',
    'access arguments' =&gt; array('access content'),
    'page callback' =&gt; 'drupal_goto',
    'page arguments' =&gt; array('http://google.com'),
  );

  return $items;
}