https://www.diamond-visions-sarl.com/page/services/lepton-cms-add-ons/comments.php
This simple comment module lets you add comments to a page.
If the user is not logged in they are redirected to a login page before they can post a comment.
An email is sent to the user if someone replies to a comment.
Users can up vote comments they like.
All comment functions are implemented with AJAX.
It is based on jquery-comments by Viima.