“Web Services division, whose server farms generate the processing power the retailer sells to heavy corporate data users on the cheap, has grown so large that the unit routinely finds itself with thousands of spare machines.
So the e-commerce giant created a supply-and-demand-driven market called Amazon EC2 Spot Instances that lets clients rent processors for as little as 10 percent of Amazon’s standard cloud-services fees. To use Spot Instances, companies bid for the rights to a certain number of servers. Winning bidders are billed by the hour, as long as the market price hasn’t risen above an upper bound they specify.
Researchers in genomics and drug design as well as online advertising increasingly use Spot to analyze terabytes of data, while companies such as Cycle Computing LLC, Princeton Consultants Inc., and Numerate Inc. have built businesses that track market prices for heavy data users.”
Other use cases for Spot in this Amazon video