NeatUpload allows ASP.NET developers to stream uploaded files to storage and allows users to monitor upload progress. It is open source and works under Mono's XSP/mod_mono as well as Microsoft's ASP.NET implementation. It features 2 custom controls:  InputFile allows the user to select a file to upload, and ProgressBar displays the upload progress either inline or in a popup. ProgressBar uses AJAX-style refreshless updates on modern browsers when JavaScript is available, but also allows users without JavaScript to see upload progress.

http://www.brettle.com/neatupload