xkcd impersonates life.
I haven't been subjected to this exact same scenario, but I have had a few times where I've needed to get my wife's attention remotely to let her know she needs to answer the phone. The Lab-O-Ratory is a noisy place, what with the rack-mount servers whirring away and all. If her phone is left on vibrate mode or is in another room, it's hard to hear it. Usually, she'd be logged into WOW or otherwise online, but not logged into AIM or GTalk, not checking her e-mail.
To get her attention, I would ssh into my DMZ box and issue the following command line:
# while true; do echo ^G > /dev/ttyC0; done
This sends a non-stop string of "Control-G" characters to the OpenBSD console (your console device may be different on other platforms), which ends up making the internal speaker on the motherboard beep until you break out of the while loop with Control-C. Fortunately, the internal speaker is loud and annoying.
To render the ^G character, you must actually hit Control-V (which means to do a Verbatim Insert on the next character) and then hit Control-G.
So yes, I am a nerd. However, my wife, in attempt to alert me that one of my computers was beeping incessantly, would find her phone, see that she missed some calls from me, and I successfully got her attention that way a few times.