Thanks to the excellent Mollom module, allowing anonymous comments on your website is a manageable task. No more spam, and all the benefits of anonymous commenting, such as the low-barrier to involvement.
However, in Drupal 7, there is one step you may have missed (I know I did). By default, the email and homepage fields on the comment form are disabled. To bring ‘em back, you have to configure your comment settings, per content type, to either allow or require anonymous poster to leave their contact information.
To do this, simply navigate to your content type settings page (for Articles, that’s at admin/structure/types/manage/article), click on the “Comment settings” tab, and change the “Anonymous commenting” setting to one of the following options:
Both will expose the email and homepage fields. (The second option makes the fields required.)
Hopefully this tidbit some a few headaches and helps to drive participation in your website.