This article assumes that you already have an Amazon S3 Storage Service account. In case you don't, it's easy to get one, just head over to this page.
Although this tutorial is done on Mac OS X, Jungle Disk is available also for both Windows and Linux and this makes it very easy to use in multi-platform environments where the user can retain a familiar interface across operating systems. To make things even better, there's a USB version available. It contains all three platforms in one package and comes pre-configured to run directly from the USB device.
Download and install Jungle Disk
The download packages are available here. Once you have the package for your operating system, install the software the usual way. On Mac OS X this means mounting the disk image, accepting the usage agreement and dragging the software icon to your Applications folder.
Now that the software is installed you're ready to start working. Assuming that you already have an Amazon S3 Storage Service account, you need to bring up the configuration screen (File > Configure) and in the first screen, named Account Settings and enter your Access Key ID and Secret Access Key as well as bucket name. New users should leave the "default" bucket name before they learn more about the service.
Your Access Key ID and Secret Access Key are shown right after you login into your Amazon S3 Storage Service account.
Connecting to your account
When launched, Jungle Disk automatically mounts as a volume named "Jungle Disk". To connect to your Jungle Disk manually, use the Finder Go > Connect to server menu. For the address, type: http://localhost:2667/ and then click on Connect.
Working with files
Once you're connected, working with files is very simple. It's basically just like working with files on your machine. The only bottleneck is the speed of your Internet connection.
You can make secure backups when needed or schedule them. In case you have a connection that needs to be used for other things beside backup, Jungle Disk allows you to limit the upload speed of your backups. Furthermore, you can automatically backup your entire hard drive or just certain folders.
Jungle Disk is shareware and has a free trial. If you like the software, a license will cost you $20 but it comes with free upgrades forever, it includes all three platforms (Windows, Mac, and Linux) and you're allowed to install it on as many machines as you want with a single S3 account.