Rackspace’s cloud server architecture has a fantastic API. I recently found a need for an automated script to have access to a server for less than an hour a day.
Within this script, I am easily able to see if there is a server ready for it already, if not, it creates a server out of an image that I have already created for this purpose, waits for the server to become active, and then it does its work.
I have a separate script that check periodically for servers running past their expired time and deletes them so that we don’t have to keep paying for them.
This will take a server from about $10/month to less than $0.50 / month.