I have developed this tool as an add-on to Servers Alive
Servers Alive is in my case located in the MER and therefore any audio/visual warnings are not noticable.
This add-on contains a small console app which can send messages over the network to a receiver.
The reciever pops up a window with the message that you sended. Just configure an alert in SA.
Of course it can be usefull for other purposes.