Windows 7 and Vista include an enhancement to the system clock that lets you display 2 additional clocks when you hover your mouse over the system clock.
Here’s an example of the London clock in Vista:
And here’s the hover clock in Windows 7:
Adding these additional clocks is extremely easy.
First right-go for the clock in the system tray, and choose Adjust Date/Time:
tap the Additional Clocks tab, and go for the options and time zone as shown:
you’re free to enter a friendly display name.
I entered “London”, but you could put something relevant to you, like the name of a family member living elsewhere.