Magento : How to add Drop-Down of Countries

Create a Country Drop Down in the Frontend of Magento

<?php $_countries = Mage::getResourceModel('directory/country_collection')
                                    ->loadData()
                                    ->toOptionArray(false) ?>
<?php if (count($_countries) > 0): ?>
    <select name="country" id="country">
        <option value="">-- Please Select --</option>
        <?php foreach($_countries as $_country): ?>
            <option value="<?php echo $_country['value'] ?>">
                <?php echo $_country['label'] ?>
            </option>
        <?php endforeach; ?>
    </select>
<?php endif; ?>

Create a Country Drop Down in the Magento Admin

<?php

    $fieldset->addField('country', 'select', array(
        'name'  => 'country',
        'label'     => 'Country',
        'values'    => Mage::getModel('adminhtml/system_config_source_country')->toOptionArray(),
    ));

?>