Aswin Anand

With this plugin, assigning multiple categories to one or more posts is a 
breeze. Pop the plugin’s PHP file to your wordpress plugin directory, 
activate it and click on “Assign Categories” under the Manage menu. 
The page will show the list of available categories, followed by the 
available blog posts. You can select the categories, select the required 
posts and then click on “Assign Categories” at the bottom of the page. 
Now, all your posts will be assigned the new categories.
Plugin Page: <a href="http://www.aswinanand.com/2008/10/bulk-assign-categories-to-multiple-posts/" rel="nofollow ugc">http://www.aswinanand.com/2008/10/bulk-assign-categories-to-multiple-posts/</a>

Assign Categories

Assign one or more categories to multiple posts in a single shot, with or without preserving existing categories.

Prasanna SP

This plugin creates a new widget which lets you show a list of recent posts based on categories or tags. This is a must have plugin if you want to exclude some categories in recent posts widget or if you want to show recent posts based on tags. By default the wordpress recent posts widget shows a posts from all category. But this plugin gives you more power to customize your recent posts widget. You can also display post date in the widget.
See the live action of this plugin on <a href="http://demo.prasannasp.net/custom-recent-posts-widget/" rel="nofollow ugc">demo site</a> or on Kennneth John Odle’s <a href="http://blog.kjodle.net/" rel="nofollow ugc">blog</a>.
Have any questions or suggestions? Create a thread in the <a href="http://forum.prasannasp.net/forum/plugin-support/custom-recent-posts-widget/" rel="nofollow ugc">support forum</a>.
Visit <a href="http://www.prasannasp.net/wordpress-plugins/" rel="nofollow ugc">this page</a> for more WordPress Plugins from the developer.
A special thanks to <a href="http://blog.kjodle.net/" rel="nofollow ugc">Ken</a> and <a href="http://www.joshlobe.com" rel="nofollow ugc">Josh</a> for testing the code.

Custom Recent Posts Widget

A widget to show recent posts list based on categories or tags

Assign Categories vs Custom Recent Posts Widget