Getting QueryString from with a module I've trying to get the querystring from within a module. 

I've tried the following.  However the following always returns A

exporter/directory?l=o

$l = "A";
if ( !empty($_SERVER['l']) ) {
    $l = $_SERVER['l'];
}


/* edit */

    $l = "A";
if ( !empty($_GET ['l']) ) {
  $l = $_GET ['l'];

}
Oswald is correct. Alternatively, in Drupal 7, you can use drupal_get_query_parameters():

$query_parameters = drupal_get_query_parameters();
if (!empty($query_parameters['l'])) {
  $l = $query_parameters['l']
}