Nick Momrik

Displays the date ad time the post/page was last modified.
<h3>Configuration</h3>
You can pass it a date/time format (http://us4.php.net/date) 
Example: <code>mdv_last_modified('l dS of F Y h:i:s A')</code>

Last Modified

Displays the date ad time the post/page was last modified.

freetools

LMP allows you to add in your sidebar a widget that will display the last modified articles in descending order of modification date.
Settings to customize:
<ul>
<li>Allow you to set title widget</li>
<li>Display Number of items</li>
<li>Display modified date</li>
<li>Display thumbnails</li>
</ul>
If no thumbnail was found for the article, LMP will add a generic image.

Last Modified Posts

Add a widget to display the list of the last modified/updated posts.

Last Modified vs Last Modified Posts