If you configured your instance you might want to save a backup of it. You can save this instance to S3 storage.

You first have to create a bucket which will hold your files (an instance will be saved to severall “zipped” parts). A great tool is s3 browser, you can download a free version here.
Just install it, and add your account access identifiers details (you can find these on the Amazon  “your account” page under “access identifiers” )
Then create a bucket, be sure to create one in the correct region (US or Europe).

Login to your AWS Management Console and, click on Instances in the left menu. You can now right click on your running instance and choose [Bundle Instance], this will bring up a pop up box. You have to provide the bucket name which you created and a S3 key name (this is just a name for your instance files, in S3 browser you will see these files as <s3 key name>.part.### ). Press [Brundle] and be prepared to wait a little while. 
You can view the status of your bundle task in the [bundle tasks] menu. Your instance will shutdown during this task, and when it is ready it will start up again.

If the bundle task is done, you can right click the bundle task and choose [Register as an AMI]. This will create a personalized AMI, which you can start and shutdown.
This is like a snapshot in VMWare.

Keep in mind that it everything on your C: drive is stored in the just created personal AMI. The provided D: drive is lost. To get more persistant disk space you have to use EBS disk space.