<h2><?php echo JHTML::link ($product->link, $product->product_name);?></h2>
<h2><a href="http://www.google.com" ><?php echo $product->product_name; ?></a></h2>
<h2><a href="http://www.my_link.com/blah/<?php echo $product->product_name; ?>.html" ><?php echo $product->product_name; ?></a></h2>