Encode Explorer is an easy-to-use phpscript to use as an index file. It shows files in the server and lets you browse through folders, upload files etc. It is kept small and neat so that the source can be used for learning.
PHP tools for developers and system administrators
The PHP Toolbox is an extensible, cross-browser script written in PHP for developers and system administrators. It was designed for rapid deployment to provide the user with on-demand tools for common server-side tasks. (http://www.phptoolbox.org)
httpFileManager is a file management script written in PHP, allowing the remote administration of files over HTTP. You may create and manage one or many Web sites. httpFileManager includes an HTML editor for the creation and maintenance of Web pages.