Procrastinator's Clock

I like the idea of the Procrastinator's Clock, which runs randomly up to 15 minutes fast. It could be right on time, or it might be reading as a full 15 minutes in the future. You never know ... unless you have another clock nearby. To get the full effect, since it's only software, you'd have to disable your system clock display (right click the clock, select Properties, untick "Show the clock", click OK).

Something like this would be very useful as a physical device too. The main problem would be that it must be the only clock in the house (otherwise you'd check and defeat it) and you can have only one (otherwise they'd disagree and you could get a more accurate estimate of the correct time).

Mokalus of Borg

PS - I guess you could have computer-controlled synchronised clocks all around the house.
PPS - If you were some kind of super-nerd.