Yarkon S3!

Cyberduck is an open source FTP client.

CloudBerry Explorer makes managing files in Amazon S3 storage EASY. By providing a user interface to Amazon S3 accounts, files, and buckets, CloudBerry lets you manage your files on cloud just as you would on your own local computer. PRO version offers FTP support.

S3 Browser - Windows Client for Amazon S3. User Interface for Amazon S3. Allows you to manage your Amazon S3 Buckets and files with ease!

Cloud Explorer is a open-source S3 client. It works on Windows, Linux, and Mac. It has a graphical and command line interface for each supported operating system.

The S3Fox Organizer(S3Fox), offers the ability to upload or download files to and from Amazon S3. The interface, which opens in a Firefox browser tab, looks much like that of FTP clients with a dual-pane layout. It displays files on your PC on the left, files on Amazon S3 on the right, and status or information in a panel on the bottom.

CloudBerry Drive is a tool to map your cloud storage as a local drive to access and edit files in the cloud directly from the Windows Explorer interface. Supports Amazon S3, Amazon Glacier, Rackspace Cloud Files, Windows Azure, HP Cloud Storage, OpenStack Swift, Goolge Cloud Storage

DragonDisk is multithreaded S3 Client with lots of useful features and an intuitive graphical user interface.

Amazon S3 gui client Bucket Explorer to create and manage bucket, for web hosting and sharing S3 files. Use it as FTP tool for S3.