Amazon EC2 has added two new instance types. Their standard instance has 1 virtual CPU and 1.7Gb of RAM for 10c (USD) per hour. The newly launched Large Instance has 4 virtual CPU cores (2 cores x 2 CPUs) and 7.5Gb of RAM for 40c per hour. The massive Extra Large Instance has a whopping 8 virtual CPU cores (2 cores x 4 CPUs) and a 15Gb of RAM for 80c an hour.
One of the beauties of the system is you can bring appliances on and off-line as you need them. You can even script your application to enlarge itself. However, the system is not without it’s drawbacks.