Quick PHP timezone juggling example.

gistfile1.php

<?php
$timezoneAuckland = new DateTimeZone('Pacific/Auckland');
$timezoneHelsinki = new DateTimeZone('Europe/Helsinki');
$currentTime = new DateTime('now', $timezoneAuckland);
$helsinkiTime = new DateTime('now', $timezoneHelsinki);

printf(
	"It is currently %s <br>", 
	$currentTime->format(DateTime::RSS)
);

printf(
	"In Helsinki it is %s<br>", 
	$helsinkiTime->format(DateTime::RSS)
);

printf(
	"The time difference is %d hours.<br>",
	($currentTime->getOffset() + $helsinkiTime->getOffset()) / 60 / 60
);

echo "All available timezones:<br><ul>";
foreach(DateTimeZone::listIdentifiers() as $timezone)
	printf("<li>%s</li>", $timezone);
echo "<ul>";