Within single control panel amazon offers various services .. S3, EC2 are mainly used web services. And recently they introduced cloud database systems called "DynoDB".
Do not start/activate any service that are not related to you. Because.. Amazon cloud will start billing you from the exact moment you initiated a service.
So., I want to know what kind of cloud solution are you looking for?
#1. CDN Cloud based content delivery? Storing media, static, image content in cloud?
#2. Run the full php application from EC2 amazon arch?