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.