A great example of using the cloud is for performance testing. As an ITS in the Bay Area I was fortunate to work with a organization that needed to test over 5,000 Virtual Users (VUs) concurrently and in a very short time and with a fixed budget. Before the cloud alternative this would have been close to impossible to accomplish and would probably have been a walk-away sale scenario for IBM.
But times have changed. Thanks to IBM's business partners, RTTS and CloudOne, we were able to offer our customer a SaaS (software as a service) that provided a cloud environment that included both the necessary hardware to perform the testing but also the RPT VU licenses - all on a monthly rental basis.
This model is something that I believe more and more businesses will chose to make as time constraints and budgets continue to shrink.