P2S3!

Cyberduck is an open source FTP client.

The SME Enterprise File Share and Sync Solution provides a comprehensive control and management solution to enable secure cloud collaboration across data points for corporations.

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!

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

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.