#4 Microsoft

Microsoft is gearing up in the cloud business with its Windows Azure Platform.  Microsoft’s cloud platform is just two years and has already made it big in the cloud market giving the top players a run for their money. The Windows Azure cloud service gives developers the option to host, develop and run web applications. Azure provides a complete set of services including computing environments, scalable storage, database functionality and a content delivery network.

#5 Salesforce

Salesforce.com has steadily been transitioning from a best of breed sales force automation (SFA) software as a service (SaaS) provider to an application development platform as a service (PaaS) company. Salesforce is a software-as-a-service provider that specializes in distributing business applications through the cloud.Force.com is a platform-as-a-service that allows developers to use the Salesforce infrastructure to develop add-on applications that integrate with the Salesforce solution. This company is well known to deliver new product features, and new capabilities, on a continuous basis.