While browsing through Sourceforge.net (something all of us should do now and then), I ran across an interesting PHP tool.
It is called "Simple File Manager (SFM)."
The author describes SFM as " a web based file management utility. Target user: Those that won't, can't or SHOULD NOT use ftp. Upload, rename, delete, folder creation, image & text viewer and mime type downloads."
This would probably be ideal for corporate sites where you want to give department heads the ability to upload files or update reports, but don't want them messing with your other files. Or maybe it would be nice for a group blog or family website.
You can download the open-source code here (http://sourceforge.net/projects/onedotoh/), and view a working demo here (http://onedotoh.sourceforge.net/demo/fm.php).
I don't have a server with PHP at work so I haven't tested this, but judging from the online demo, it would be a great tool to have on-hand.