1. Amazon Elastic Compute Cloud,
http://aws.amazon.com/ec2/
2. Salesforces Force.com Cloud Computing Architecture,
http://www.salesforce.com/platform/
3. Google App Engine,
https://appengine.google.com
4. Windows Azur Platform,
http://www.microsoft.com/windowsazure/
5. Apache Cassandra,
http://cassandra.apache.org/