Until (if ever) such a feature is added to PerlMonks, you can use JavaScript to manipulate the DOM objects to attain the desired effect. Add the code following to your Free Nodelet. Make sure your Free Nodelet is being displayed.

<script type="text/javascript">
// ========================================
// Move nodelets to the left side.

function move_nodelets() {
   for each (var td in document.getElementsByTagName('td')) {
      if (td.className != 'nodelets')
         continue;

      var tr   = td.parentNode;
      var main = tr.firstChild;

      tr.insertBefore(td, main);
   }
}

move_nodelets();
</script>
[download]

Tested successfully in FireFox 1.5.0.7.
Tested unsuccessfully in IE 6.0.2900.2180.xpsp_sp2_gdr.050301-1519, although I'm sure it could be made to work by someone more knowledgable.

Update: Clarified Until => Until (if ever).
Update: Title change.
Update: An updated version of this code found in Re^9: Free Nodelet Hack: Nodelets on the left. The core logic has been simplified and it has extra logic to delay execution to a safe time (allowing it to work in IE).