I started off using the Firefox Addon S3Fox to upload files from my desktop PC to my S3 distribution. I didn't much like it - partly because it was just an addon, and therefore closed with Firefox, but partly because it was pretty lacking in functionality, and overall was pretty sluggish to use. (Screenshot).

I had used the Manager for Amazon CloudFront - which was pretty good for basic stuff, and uploading the odd file. One major flaw of this software though was that it has no kind of queue system, making tasks like uploading the FamFamFam icon set impossible, given that I'd have to upload 1,000 files individually. (Screenshot).

Then I found the CloudBerry Explorer after quite a long session of Google searching. This software seemed too good to be true, it did everything that I needed in a free desktop application, and much more. Every feature of Amazon S3 is accounted for as far as I can see - from Access Logging to setting the headers of certain files, it's all there. CloudBerry Explorer also is amazingly fast, which, coupled with a file queueing system knocks the socks off S3Fox's speed.

The software also easily integrates CloudFront Distributions - giving your bucket a different icon if it's part of a distribution.

All in all, the software is awesome for a free piece of kit. (Screenshot showing S3 and CloudFront distributed buckets).