This is a list of the current Drupal 7 supported themes available here at ThemeForest. It will grown soon... you'll see. Many of the current D6 will be ported and more will be added. If you're interested on porting any other theme (Wordpress based...
These are the Drupal 6 themes I like the most of ThemeForest. It would be awesome to see them ported to Drupal 7...