Since the EC2 platform is administered via web services some people have come out with some handy tools to make it easier. If you are running Firefox this one is a must have. Sure beats the dos based tools that I started using. This tool is useful even if all you do is start it up to make sure you don’t have any instances still running that you didn’t know about which would be racking up a bill.

http://developer.amazonwebservices.com/connect/entry.jspa?externalID=609