MySQL Replication monitoring
You could quite easily write a simply Perl or PHP script, running on a cron, to periodically check the MySQL server and alert you to any problems.

For example, I have the following Perl code in my setup:

$sql="show slave status";
$sth=$dbhread-&gt;prepare($sql);
$sth-&gt;execute();
($result)=$sth-&gt;fetchrow_hashref();
$sth-&gt;finish();

if($result-&gt;{'Slave_SQL_Running'} ne "Yes") {
   &amp;SendAlert("Slave SQL not running");
}

if($result-&gt;{'Slave_IO_Running'} ne "Yes") {
   &amp;SendAlert("Slave IO not running");
}

if($result-&gt;{'Seconds_Behind_Master'} &gt; $threshold) {
   &amp;SendAlert("Seconds Behind Master is too high");
}


Obviously &amp;SendAlert can be set up to do what ever you like (email/SMS alerting)