Wayback Widget
The Wayback Widget is a widget for WordPress that can display all posts that happened around the current day in the past. Default is to display all posts from this week a year ago.
To install download the file, rename it to “wayback-widget.php”, put it in your “wp-contents/plugins/” directory and activate the plugin in the admin interface. Then you can add the widget to your theme.
This is licensed under the GPL since it is based on the GPL cg_wayback function by Chris Goringe.