This a very simple plugin usable for showing the files within a directory (a bit like the Index generated by Apache). It's easy to extend to add more functionality like image icons for file types.
Just copy the file directory-listing.php into the wp-content/plugins folder and activate it in the Plugins-View of your Wordpress administration interface.
This plugin uses the filter hook. In the content field of the page or post, add the following line:
The default installations assumes that you a folder called files within the wp-content directory. The line above therefore shows all files within the folder wp-content/files/ path/to/my/directory.
Right click and Save As: http://www.q14.net/etc/wp-directory-listing/directory-listing.zip