Kerfred

Displays the current rewrite rules for the site. Requires the debug bar plugin.

Debug Bar Rewrite Rules

Displays the current rewrite rules for the site. Requires the debug bar plugin.

Robert O'Rourke

interconnectit

In addition to controlling your custom post type permalinks this plugin adds support for using custom taxonomies in your permalink structures as well.
Not only that but you can control the full permalink so the post type slug is not required at the start of the link.
Multiple post types can use the same permalink structure.
<h4>Usage</h4>
There are 2 ways to use this plugin:
Permalink Settings
The plugin adds fields to the permalinks settings page for any public facing custom post types.
In Code
When registering a post type you can add a value to the rewrite property with the key ‘permastruct’ to define your default permalink structure.
eg:
<pre><code><?php

register_post_type( 'my_type', array(
 ...
 'rewrite' => array(
 'permastruct' => '/%custom_taxonomy_name%/%author%/%postname%/'
 ),
 ...
) );

?>
</code></pre>

WP Permastructure

Adds the ability to configure permalinks for custom post types using rewrite tags like %post_id% and %author%.

Debug Bar Rewrite Rules vs WP Permastructure