wphobby

Main Features:
<ol>
<li>List comment subscriptions email, post name, date.</li>
<li>Ban or Active the subscribers.</li>
<li>Modify email notification subject, body, footer by tags.</li>
<li>Modify email styles, include body background, text color and footer background.</li>
<li>Change the display text on the end of comment area.</li>
</ol>
More info:
<ul>
<li><a href="http://plugins.wp-coder.net/purchase/comment-notice/" rel="nofollow ugc">Leave a comment</a></li>
</ul>

Comment Notice

The main function of this plugin is to display a subscription option on the end of the comment area, so they can be noticed when there are new commen …

genkisan

<ul>
<li>easily switch on and off through Admin Options</li>
<li>display message without editing theme files (above 1st post or through widget)</li>
<li>display different message to different roles/users</li>
</ul>
Demo: 
<a href="http://ericulous.com/2007/03/09/genki_announcement/" rel="nofollow ugc">Plugin Details & Demo</a>

Comment Notice vs Genki Announcement