The pager idea is the first thought that came to mind. I remember how useful those
old AT&T pagers were way back in 1995, etc…
Maybe you can strap a pager or something that vibrates like one of those
Logitech USB gamepads which vibrate and write a script or something that makes it
vibrate in intervals…
You can also use a webcam with built in microphone and somehow program it so that it has/uses
“motion sensing” and “sound sensing” and you wrap a headset around the mic playing
Beatles’s “let it be” in loop mode… For the motion/movement sensing just point
the camera at a mini electric fan or some type of television set and it will keep on looping, etc…
Another solution is a bit more complicated and risky but you can invent
a “mini earthquake desk” that vibrates in intervals…And just for fun…
it doubles as a possible rocking bed platform for a baby so you don’t have
to wake up and get out of bed at 3 A.M… This would also be motion and sound
sensing. (I dunno if this is morally responsible/acceptable design though… )
You can alternatively just either pay or promise to take out one of your co-workers
on a date and have or her move the mouse for you… Helps improve your social
and networking skills! 
Finally If you want something cheap, useful and free just use “ping” software
and type in the command ‘ping localhost’… 