Relating to this question, Upload files directly to Amazon S3 from ASP.NET application, is there any way to do this and have a progress bar?
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Two days later and still no luck with a direct way. Found one thing that looks promising but not free: http://www.flajaxian.com/
Uses flash to upload directly to S3 with a progress bar.
Another approach is to use something like Uber Uploader (http://uber-uploader.sourceforge.net/) which is a perl / php hybrid solution with a progress bar. You would simply upload the files to your server and then have your server FTP them in the background to the final destination. It is an extra step but it gives you some time to do any processing / encoding / etc. that you may need to do before sending to S3.
I'm looking for a solution as well. Maybe this will be of some help,
Update: It looks like there are two straightforward options.
I personally hate using 3rd party extensions (Flash, Java) to make an app function, but I haven't found another way.
html5 javascript can allow you to do it, if you don't mind lack of browser support (Firefox and Chrome only as of this post_ Example here: https://developer.mozilla.org/en/Using_files_from_web_applications
This isn't specific to AWS, but may help you get closer.