Umm don't know of a script someone has published but it's a simple concept.
Use htaccess...
Create a file called .htaccess and put
ErrorDocument 404 http://www.yourdomain.com/show.php
in the file. This will pick any pages that don't physically exist on your site and redirect it to the show.php page
Then in your show.php page show the database results based on the number from $REQUEST_URI
Hope this helps