php File Manager is an open source web file manager. A commercial version with newer updates is available on the website. php File Manager forked from a project on phpfm.zalon.dk (site is no longer available).
From the Author
php File Manager, based on the script written by phpfm.zalon.dk, is an open source, web-based File Manager.
Authors website: http://www.installatron.com/itronscripts