Read about the Wesley's clock in Harry Potter?? How, instead of having hour, minute and second hands, the clock has hands for each member of the family.. and around the clock.. it has places/locations.. eg.. office, school, home.. whatever.. and so.. the hands for each member will be pointing to the locations.. or even in mortal peril (if ever caught in the situation).
Sounds a bit far fetched? Seems that it might be a reality in the near/distant future. Microsoft researchers recently showed off a digital clock that is like that.
Seems that that project was truly inspired by the Wesley's clock.. and there's no doubt that if that clock truly becomes available in the market.. we'd have lots of things to answer for..
"Why were you at XXX's when you told me that you'd be at work??""