For companies considering cloud computing, the biggest monkey wrench in the works tends to be security. IT and business leaders alike worry about security concerns such as the protection of sensitive data, access control and identity management, regulatory compliance, the complexities of multitenancy, and how to determine best practices despite a lack of mature standards in the industry.

But cloud providers will soon begin building security into their offerings, says Jonathan Penn, an analyst at Forrester Research, and those concerns will likely change. As security vendors develop offerings that cloud providers can use to secure systems, applications and data, Penn sees cloud security developing into a $1.5 billion market by 2015. At that time, he writes on his blog, "security will shift from being the number-one inhibitor of cloud to one of the top enablers and drivers of cloud services adoption."

Until then, companies that have decided to take the plunge are grappling with security issues on their own. Unexpectedly, some of them are finding that by doing their homework, they can create higher levels of security in the cloud than they had in their old environments.

Here is a look at three companies that have moved applications, infrastructures and data into the cloud.

* Case 1: Mohawk Fine Papers

Manufacturer strives to protect applications via closer relationships with its cloud providers

* Case 2: BuildFax

Property history company layers monitoring and other security services on top of public cloud offerings

* Case 3: Inavero

Small research firm meets different security challenges in different cloud models

And for more cloud cases, see Hybrid cloud computing security: Real-life tales.

Read more about cloud security in CSOonline's Cloud Security section.