To deal with instances on Amazon EC2 you need the Amazon EC2 API Tools. You can download it here:
This command line tools are used to access the EC2 instances. To use this tools you need Java 1.5 or higher and you need to setup the System Variable “JAVA_HOME”. How to set up the tools with the certificates you can read in the User Guide.
I used already the S3 Storage from Amazon together with an Ruby on Rails App to store images. It worked pretty good for me. Now I am experimenting with EC2, the Elastic Cloud Computing. Here are some good links to start: