Directory structure:

Stored as:
IdParentName
31Countries
43Belgium
53Netherlands
63Germany
75Business and Economy

Retrieve list with:

<?php
    function gimmeParent($id) {
        global $dir;

        $res = mysql_query("SELECT parent, name FROM directory WHERE id = $id");
        if (mysql_num_rows($res) > 0) {
            $dir[] = ($row = mysql_fetch_row($res));
            gimmeParent($row['parent']);
        }
    }

    gimmeParent(7);
?>