Who is using EC2 for his startup? And how are you actually manage your platform? Is the EC2-Console sufficient? Do you use RightScale or CloudClick? Any other open-source tool? What are the shortcoming of those tools?
We run our online MMORPG, Star Sonata, on it. We just use the console since we're not really changing our instances much. We just use it because it has great ping times and bandwidth and the largest high-CPU instance is just perfect for our server.