Note: This plugin is no longer under active development. If you're interested in maintaining it, please contact me.
Repair 404 Errors WordPress Plugin simply notifies you of any page or file requests that a user (or search engine) makes to your blog.
If it can't find the right file or page it captures that failed request into the plugin so that you can easily go and fix the issue manually.
After you fix the issue you can then hit the Repaired button to let the plugin know that you've handled the problem.
Read more here!