AJAX Upload Allows you to easily upload multiple files without refreshing the page and use any element to show file selection window. It works in all major browsers and doesn’t require any library to run. >>>, simple usage example: >>>
* Those below are not JQuery-dependent, but still quite interesting...
fileuploadarea Uses the new File API supported by Firefox 3.6. Enables you to target any html element and turn it into a hotspot for receiving files from the file explorer! Each file will be sent as a binary AJAX-request with customizable GET params. Includes support for callbacks to track the progress and completion of the file. >>>
LightLoader This employs a similar method to what is found in the GMail file upload, using a hidden IFRAME to post the file and AJAX to check the progress. There is also a tester script in the zip file for you to upload to your server to make sure that you have all the settings correct. Instructions are also in the zip file. >>>
* Couple of upload components with extended features and/or file management mix-ins, AFAICS require perl backend.
XUpload is an advanced upload progress bar indicator for web based file uploads written on Perl. XUpload lets you to accept file uploads on your website and shows upload progress bar which is showing upload progress in real-time. >>>
FileChucker is an AJAX-based web application that lets you accept file uploads on your own website. It's simple to install, packed with features, fully configurable, nice looking, and very handy for when you want to share files with anyone. And during uploads FileChucker shows a progress bar & table, so the user knows how much time is left before the upload is complete. >>>