Who uses the service: Software companies Epicor, S3Edge and Micro Focus are among the early customers using Azure to develop cloud apps.~~

Company name: NetSuite 

Founded: 1998

Location: San Mateo, Calif.

Cloud offering: A business software suite including e-commerce, CRM, accounting and ERP tools.

Why we're watching it: One of the industry's most successful online business software providers, NetSuite has a tendency to make competitive moves that are both entertaining and potentially profitable for customers. NetSuite recently promised 50% discounts to Sage Software customers who switch to NetSuite, and made a similar offer to Salesforce.com and SAP customers last year. NetSuite will even integrate with rivals' technology, for example by connecting its ERP suite to Salesforce's CRM tools, a move designed to lure Salesforce customers by enabling new business processes.

CEO: Zach Nelson, appointed in 2002 after holding executive positions at companies such as Oracle and Sun.

How NetSuite got its start: NetSuite, originally called NetLedger, was founded by Oracle CEO Larry Ellison and NetSuite CTO Evan Goldberg to make Web-based applications for small businesses. NetSuite and Oracle had tight go-to-market partnerships in the company's early years but Ellison's official influence over the company has diminished since NetSuite went public late in 2007. 

Who uses the service: Thousands of small business and enterprise customers worldwide including Wolfgang Puck Coffee, Wrigleyville Sports and Isuzu.

Company name: Rackspace 

Founded: 1998

Location: San Antonio

Cloud offering: The Rackspace Cloud, also known as "Mosso," consists of three major services: Cloud sites, a platform for building Web sites; Cloud Files, a storage service; and Cloud Servers, an Amazon EC2-like service that provides access to virtualized server instances.

Why we're watching it: Rackspace has a long history of offering hosted data center services and is a trusted name in the enterprise. With Mosso, Rackspace is taking aim at the platform-as-a-service and infrastructure-as-a-service markets, the two key areas for customers looking to build Web-hosted applications.

CEO: Lanham Napier, joined Rackspace as CFO in 2000 and became CEO in 2006.

How Rackspace got into cloud computing: Rackspace has always focused on providing dedicated, rather than shared, data center resources. That is, until a small team in the company said, "There has to be a better way for Web designers to build Web sites rather than getting a dedicated server" that requires extensive management, according to Rackspace CTO John Engates. With a multi-tenant cloud service, Rackspace can offer as-needed access to computing resources for one-off projects. "Cloud looks a lot like our business today, it's just changing how it's sold," Engates says.