* per-user settings can be stored in a more or less standard way using hook_user and/or user_save
  * something strange in PHP. It seems that global arrays defined in an INCLUDED files are local to the included file and their range disappears in the including file:

<code php>
<?php
// foo.php
$ar = array('alice', 'bob') ;

function baz()
  {
  global $ar ;
  echo is_array($ar) ? 'True' : 'False' ;
  }
?>
</code>

<code php>
<?php
// bar.php
include 'foo.php';

baz();
?>
</code>

<code php>
<?php
// qux.php
require 'foo.php';
baz();
?>
</code>

  * qux.php displays True as expected.
  * bar.php displays False (???)
  * bug, feature, or test error ?
  * Tested with PHP 5.0.4