Computing compute resources for a startup vs Amazon
blog.summize.com
blog.summize.com
The totally legitimate and efficient uses of EC2/S3 are few and far between. Mostly things like Justin.tv, where their peak load is so much higher than their average.
The best thing Amazon has done with EC2/S3 is give the architecture astronauts a datacenter-holodeck, where they can safely live out their fantasy scaling scenarios.