Note: this is a "vintage" tip for older computers/systems.
Warning! This hint is horribly obsolete. If you are still using a system as old as System 7, please upgrade to a new OS as soon as possible!
Always set your location in the "Map" control panel because some programs (such as Eudora) use this to calculate time information based on your zone, and other information. On more modern systems the map control panel is replaced by the Time Zone tab in the Date and Time preference pane. Note that even if you use a newer OS, setting your location is still important.
To show an enlarged map in the "Map" control panel hold down the option key while running the control panel.