<?
@mysql_connect("serveur","login","pass");
@mysql_select_db("ma_base");

/* nombre d'éléments à sélectionner aléatoirement */
$nb_elements = 3;

$requete = mysql_query("SELECT * FROM ma_table ORDER BY rand() LIMIT ".$nb_elements);
while ($row = mysql_fetch_row($requete))
{
echo $row[0]."<br>";
}
?>