[rajasaur]

And that you dont have to worry in case your site get a spike due to it being slashdotted.

The other advantage I can think of is to see if a better configuration would help scalability needs. For e.g. if I think a x-bit x-core box would work better for my app, there isnt a need to buy the whole thing before knowing it does no good. I could just pick one from the cloud and pay only for usage.