Now that you understand how this comments plugin works, feel free to fork it and build your own comments plugin!
Here are some potential features that you might want to build.
Add the ability to create and manage blog posts directly from a web interface.
Currently only the website owner can enable comments. You could create a social news website or forum where users can submit topics and enable comments for their own topics. The appendable data would be associated with the topic owner, so they would be able to manage the comments associated with their topic.
Currently you need to maintain a separate blacklist for each page. You could modify the plugin to use the same list of blocked users for all pages on a given website.