Amazon EC2 is a web service that provides resizable compute capacity ... It is designed to make web-scale computing easier for developers.Not sure what this has to do with selling merchandise online, but it is pretty interesting.
Just as Amazon Simple Storage Service (Amazon S3) enables storage in the cloud, Amazon EC2 enables "compute" in the cloud ... It provides you with complete control of your computing resources and lets you run on Amazon's proven computing environment ... Amazon EC2 changes the economics of computing by allowing you to pay only for capacity that you actually use.
See also the Alexa Web Search Platform, which also allows computing and storage on Amazon's servers, and the Sun Grid Compute Utility.
[Found via Philipp Lenssen]