I work with multiple time zones in mind. To help, I use widgets and menu items to keep me in sync.
The easiest way to keep an eye on different timezones is to add them to Ubuntu's time and date applet. By the end of this post you will know how to add, edit and remove timezones on the Date & Time menu in Ubuntu 12.04 and 12.10.
A recent update to Ubuntu 12.10 has brought subtle improvements to the default "date and time" applet. The Indicator Datetime menu has supported the listing of "other locations" for several releases, but it's only with this update in Ubuntu 12.10 that an options to choose how they are sorted has been available.