For the new, featured and specials modules you could always just add it to:
includes/templates/YOUR_TEMPLATE/common/tpl_columnar_display.php
at the very end, find the:
Code:
<br class="clearBoth" />
change to:
Code:
<br class="clearBoth" /><hr />
or look in the add-on section for
column divider pro
hope this helps!