File Manager With PHP & jQuery: SFBrowser
SFBrowser is an open source application, built with PHP and jQuery, for managing files online with an Ajaxed interface.
Besides listing files and folders, it can upload, delete, rename and preview them. Uploading can be accomplished via an Ajaxed or Flash-based uploader (queued multiple uploads, progress bar, canceling, selection filtering, size filtering).
The functionality can be extended with plugins. There are few ready-to-use ones like filetree and image-resize.
For a faster usage, there is a context menu and support for keyboard shortcuts.
It is a multilanguage application, new languages can be added by creating new localization files (English, Dutch or Spanish are already included).
P.S. It is also available as a WordPress plugin.