You can often see several clocks with Moscow, London, Berlin, New-York, etc. time hanging above the hotel's reception. That's is made for the businessmen so they could be able to know what time is it in another part of the world. This calculator can display the time in different cities as well, using Cities Handbook.
How to use
Enter hours and minutes in 24 hours format and choose a city, f.e. Moscow. Then choose a second city, f.e. "Khabarovsk". Note that results can be wrong if cities are from different countries due to different winter/summer time change dates.