WordPress.org

Copy the timezonecalculator directory into your WordPress Plugins directory (usually wp-content/plugins). Hint: With WordPress 2.7 and higher you can conduct this step within your Admin Menu.

In the WordPress Admin Menu go to the Plugins tab and activate the TimeZoneCalculator plugin.

Navigate to the Settings/TimeZoneCalculator tab and customize the timezones according to your desires.

If you got widget functionality just drag and drop TimeZoneCalculator on your dynamic sidebar in the Appearance Menu. Otherwise, put this code <?php getTimeZonesTime(); ?> into your sidebar menu (sidebar.php) or where you want the results to be published.

Be happy and celebrate! (and maybe you want to add a link to http://www.neotrinity.at/projects/)