This should work, not tested!!!!!
<?php
include_once(dirname(__file__) .'/globals.php');
$usercount = mysql_result($db->query('SELECT `userid` FROM `users` ORDER BY `userid` DESC LIMIT 1;'), 0, 0); // get the last userid
//sometimes $db->fetch_single doesnt work ;)
for($i=1; $i<=$usercount; $i++) :
$db->query('INSERT INTO `monkeys` VALUES ('', '. $i .', 10, 10, 10, 10, 0);');
endfor;
$h->endpage();
?>