This widget will display the recent comments on Blogger blogs (free-hosted or self-hosted).
Steps:

1. Go to your Blogger Dashboard > Layout > Page Element > Add a Gadget > HTML/JavaScript

2. Copy and paste the code below:

<script style="text/javascript" src="http://www.freewebs.com/filer/blogger/rc.js" ></script><script style="text/javascript" >var a_rc=5;var m_rc=false;var n_rc=true;var o_rc=100;</script><script src="http://YourOwnB1og.blogspot.com/feeds/comments/default?alt=json-in-script&callback=showrecentcomments" ></script><div;><small>↑ <a href="http://www.crapattack.org/2009/05/how-to-create-recent-comments-widget.html">Grab This </a><a href="http://www.crapattack.org/" target="_blank" title="Recent Comments Widget">Widget</a></small></div>

3. In the code, look for the line:

…src=”http://YourOwnB1og.blogspot.com/feeds/comments/default…

…and replace the blog address (indicated in color blue ) with your own blog address.

4. Add a title. Save.

Number of Comments
This widget is set to display 5 recent comments. If you want to change that number, just look for the number 5 in the code and replace it with the number of comments you want to be displayed. I recommend setting it between 4 and 8.

… a_rc=5;var m_rc=false;var n_rc=true;var…

Number of Characters (Excerpt)
This widget is set to display an excerpt of 100 characters of each comment. If you want to change that number, just look for the number 100 in the code and replace it with the number of characters you want to be displayed. *

n_rc=true;var o_rc=100;

*Recommended setting: 50 to 100.