Recommended by Thad.
First let me say that I have no financial ties to the company, For for that matter any ties except I use their software.
When playing on a server like IGS or KGS, you encounter events in different time zones. Figuring out the local time can get confusing. So it helps to have a set of clocks set to different cities.
Clox is one such piece of software. ( Your comuter system clock must be correct, but you can set that via ntp server and several clients. I will others make that recommendation. )
The software is free to use as long as you don't mind the nagging when it starts up. or you can buy it and make that go away.
I looked for something like this after an episode of the West Wing. In that episode the President was on a trip to Tokyo. The staff had an emergency that required them to know what time it was in Tokyo. They were debating the time when one interrupts and tells them to look at the clocks on the wall behind them. Including one set to Tokyo time.
Does this merit its own page? This is stretching the Go tie a bit, a simple search on google will yield enough useful sites.