While it may look like a friendly robot that would be taken in by Hume Cronen and Jessica Tandy, this little USB device is a "Posture Correcting Alert Device" that sends off a chime and a flashing LED when you get closer than you should be to the screen. That won't get annoying at all! (You can set the preferred distance, though.)

$22 will get you one from UXSight.com, although you'd be better off just not ever leaning forward in your chair.