New Plugin – Rewrite Viewer

This plugin has a very specific purpose – to generate a list of the current rewrite rules that WordPress is using. Unless you are writing WordPress plugins that support permalinks, this plugin will probably not be that useful to you. But if for whatever reason you need to check the rules (for debugging.. troubleshooting..) it will do the job nicely. Only newer versions of WordPress store the rules internally of course. If you have a much older version, the data will simply be in your .htaccess file.

http://www.dagondesign.com/articles/wordpress-internal-rewrite-viewer-plugin/

All you do is enable it, and browse to:
http://(your wordpress install)/rewrites/

Example: http://www.dagondesign.com/rewrites/