Amazon’s S3 service is incredible because of it’s incredibly scalable object storage infrastructure. Unlike consumer facing services like Dropbox there’s very few ways of managing it outside of the command line interface.
I’ve found a nice software which helps in bulk updating objects in S3 (e.g. change object’s metadata).
I love that it supports Windows, Mac OS X and Linux. It has a graphical user interface that’s very similar to windows and can fully support file versioning and file synchronization. Files can be compressed and encrypted.
It’s called DragonDisk and is available here: http://www.s3-client.com/