Some time ago I did a little hacking around and came up with a way to insert a progress bar when uploading files: archived forum thread
This was EE1 only, and used the now defunct (and very missed!) nGen file field. Recently I’ve been struggling with file issues on an EE2 install so I figure I’d give it a shot. I’m pretty happy with the results: safecracker file field with progress bars
Essentially, it uses a PHP extension called updateprogress to track the file upload, and jquery to poll the info and inject the display into the form.
If there’s any interest I’ll try to post some more info, although it’s essentially the same as the last time. 😊