How about better ‘inline’ user-registration for guests.
By ‘inline’ I mean that users can save login info (register) whilst making their first comment if they so desire. Usually having people register before commenting makes everything more controllable for a solo-admin but directing people to the wp-login.php page to register (which is not in any way linked to the theme of your blog, another new feature, perhaps?) is not very user-friendly and I think discourages many from wanting to write a comment/question.
