S3:// is a new extension available on addons.mozilla.org for interacting with Amazon's S3.
Rather than a conventional FTP-like interface (provided by S3Fox), s3:// uses the urlbar to interact with S3.
By going to s3:// you can add your Amazon S3 credentials and then manage your buckets, upload new files, or delete existing files.
Please join me at s3:// google group if you have problems or ideas!
If you are a coder, the code is located at github.