Plupload - Multiple Files Upload Script
Plupload is an advanced open source JavaScript component for file uploads. It has the unique feature of supporting multiple upload methods including: HTML5 Gears, Silverlight, Flash, BrowserPlus and normal forms. Other features include: upload progress, image resizing, multiple file uploads and chunked uploads. Plupload unique features makes it highly usable upload handler for Content Management Systems or similar solutions.

Plupload is currently separated into a Core API and a jQuery upload queue widget this enables you to either use it out of the box or write your own custom implementation. Drag & Drop support of files is currently only available in Firefox 3.5+. Image resizing is only possible on Firefox 3.5+ and only at a fixed quality.
Developed by Moxiecode Systems – the developers of TinyMCE WYSIWYG Editor; Plupload is available for download under GPL2 License. You can find further information, demos & download on Plupload Website.