Код для вывода случайного поста из форума на главную страницу:
$q = mysql_query("SELECT COUNT(*) FROM `forum` WHERE `type` = 'm' AND `close` != '1'");
$c = mysql_result($q, 0);
$num = rand(0, ($c - 1));
$post = mysql_query ("SELECT `user_id`, `from`, `time`, `text` FROM `forum` WHERE `type` = 'm' AND `close` != '1' LIMIT " . $num . ", 1;");
$post1 = mysql_fetch_array($post);
echo '<a href="anketa.php?id='. $post1
['user_id']. '">'. $post1 ['from']. '</a> ('. date("d.m.y H:i", $post1['time']). ')<br/>';
echo $post1['text'] . '<br/>';