This plugin lets you redirect pages to an external or an internal URL, simply by adding a custom field to a page, with the URL as the value of that custom field.

The plugin does two things:
1. It redirects (301) the page to the custom URL
2. It replaces a page's permalink with the custom URL wherever the permalink is used.

For instance, when using wp_list_pages or wp_page_menu, or even just the page list widget, when you hover over that page's link, you won't see that page's normal permalink, but rather the custom URL that you inserted into the custom field.

Common uses for this plugin would be: 
1. Adding external links to your menu bar without having to edit code. Just create a new page and use the custom field to send users to an external link.
2. Adding internal redirects to certain sections of your site.  For instance, you could create a page that redirects to a certain category archive in your blog.

In order to use this plugin, simply insert a new custom field with a name of "redirect" and paste the URL to which you want to redirect into the value box.  Save the page, and you're done.  The plugin takes care of the rest.