Server Explorer lets you upload files to Amazon S3.

You can manage your editor content in Amazon S3 in three easy steps:

1) Set up an account for Amazon Simple Storage Service (S3).
2) Add the configuration settings from AmazonS3Config.xml to your Web.config file and
    change the settings with your own Amazon access key id and secret access key.
3) Set the EnableAmazonS3 property of your UltimateEditor control to True.

Please visit User Permission (Amazon S3) sample to see how you can control user access to files in Amazon S3.