Back in July of 2009, I wrote about my experience of deleting a field within my database that unknowingly, was important for WordPress to have. The field is called comment_karma. At the time, I had no idea why this field was important to WordPress. Today, I stumbled across an article on True/Slant that explains their use of this particular field with AJAX to curate and filter comments. They provide the code snippets along with explanations as to what the code does.