<?php
class Something
    extends Mage_Adminhtml_Block_Widget_Grid_Column_Renderer_Abstract
{
    public function render(Varien_Object $row)
    {
        $column_data = $row->getData(
            $this->getColumn()->getIndex()
        );

        return $this->getLayout()
            ->createBlock('something/adminhtml_renderer_link')
                ->setLink($column_data )
                    ->_toHtml();
    }
}
?>

<?php
class Something
    extends Mage_Core_Block_Template
{
    protected function _construct()
    {
        parent::_construct();
        $this->setTemplate('something/link.phtml');
    }
}
?>

<?php
$link = $this->getLink();
?>
<?php if ($link): ?>
<a href="<?php echo $link ?>" target="_blank"><?php echo $this->__('Click to view!'); ?></a>
<?php else: ?>
    <?php echo $this->__('No link'); ?>
<?php endif; ?>