Jeff Barr pointed to Sergey Schetinin's S3 Manager (he's looking for beta testers).
The screenshot included in this post is not of Sergey's project - but a demo project that comes with the /n software's IBiz S3 Integrator.
The IBiz S3 Integrator is a component toolkit for software developers that allows you to easily add Amazon S3 capabilities to your own applications. The toolkit comes with the development component as well as the a demo, such as the one you see here.
This particular demo allows you to browse and manage your S3 buckets, and browse and manage objects contained within those buckets.
You can read more about and download the /n software IBiz Amazon S3 Integrator here. You can read more about Amazon's S3 service here.