In a web site where only authenticated users have access to content and comments it may still be required to let authenticated users comment anonymously.
This small module adds the option for the administrator to allow anonymous commenting by authenticated users for specific roles on specific content types.
Where allowed, users get a choice, on the comment creation form, to post their comment anonymously.
Such comments are assigned the anonymous user id but the log will still show the creation of the comment by the authenticated user which makes it a bit less than completely anonymous and allows for some moderation. Within a trusted site membership such feature may encourage more participation with little risk of misuse.
Download Drupal 6 module: anonym_comment.tar.gz