timezone_select.php

<?php

static $regions = array(
    'Africa' => DateTimeZone::AFRICA,
    'America' => DateTimeZone::AMERICA,
    'Antarctica' => DateTimeZone::ANTARCTICA,
    'Aisa' => DateTimeZone::ASIA,
    'Atlantic' => DateTimeZone::ATLANTIC,
    'Europe' => DateTimeZone::EUROPE,
    'Indian' => DateTimeZone::INDIAN,
    'Pacific' => DateTimeZone::PACIFIC
);
foreach ($regions as $name => $mask) {
    $tzlist[] = DateTimeZone::listIdentifiers($mask);
}

echo '<select>';
echo '<option>Pick your timezone</option>';

$count = 0;
foreach($tzlist as $timezones) {
  foreach($timezones as $timezone) {
    echo '<option value="' . ++$count . '">' . $timezone . '</option>';
  }
}

echo '</select>';