CMS Lounge have just updated all their Drupal themes and created a separate version for each one that works with the new version of Drupal, Drupal 6. This new release of Drupal is still a release candidate (which means that you should likely not use it in a live site just yet), but that has not stopped us from porting their templates to it.

They also have free Drupal themes available for Drupal 6 now.