If you want a quick way to show off your number of comments you can add this to your sidebar.php

 
<?php 
$commcount = $wpdb->get_var("SELECT COUNT(*) FROM $wpdb->comments WHERE comment_approved = '1'"); 
 
if (0 < $commcount) $commcount = number_format($commcount); 
echo "Our users have made ".$commcount." comments, care to join in?"; 
?>