<?php
//...
$q_1=mysql_query("SELECT id_link FROM consentiti WHERE id_utente='$id_utente'");
while($riga_1=mysql_fetch_array($q_1)){
$q_2=mysql_query("SELECT link FROM link WHERE id_link='".$riga_1['id_link']."'");
while($riga_2=mysql_fetch_array($q_2)){
echo "<a href=\"http://".$riga_2['link']."\">".$riga_2['link']."</a><br>";
}
}
//...
?>