There are a number of world time zone maps and clocks available online. Exportaid uses a number, including http://www.worldtimezone.com/ and http://www.worldtravelguide.net/clock/ to constantly remind us of the time differences between our UK base and the rest of the world. We plan our communications with associates and clients in different countries so that everyone knows in advance when they need to be available.
Russia covers seven time zones, North America six, Africa four, and Australia three. So not only does communication need to be planned but also your travel. Most importantly, you need to know when and where your customers will be available to meet with you. By understanding their timetables and the cultural issues that may impact on that timetable, you can save yourself a lot of time and money.