Cloud computing offers a lot of advantages to companies that don’t want to run their own data centers. AppZero, one of the companies presenting this week at DEMO 2009, hopes to make it much easier for companies to move their sites and applications between different data centers.

Call it cloud hopping. The company hopes to save companies money on hosting and backing up data using its new virtualization technology, which adds an infrastructure layer so that applications can run freely without regard to underlying hardware. For instance, sometimes companies need a second data center to back up the first one. They can use the cloud for that, but it is sometimes tough to make the transition.

Jersey City, N.J.-based AppZero makes it easy for data center administrators to move applications from their own data center to the cloud servers, and then to another location, as if they were dragging and dropping icons from one server to another. The application then runs in the appropriate data center.

Mark Yohai, vice president of sales and business development, said that the AppZero technology — formerly named Trigence — makes it easier for companies to deal with disaster recovery, backup, and reallocation of servers based on peak work loads. For instance, if you have to test some applications three months out of the year, it doesn’t pay to have them running on your own data center all year long. Instead, you can run them as needed on cloud servers and pay only for the usage during the three month period.

You can also reallocate from one server cloud to another, based on costs. Yohai said that gives companies more agility. Appzero was founded in 2004 under the Trigence name. It started with a focus on Solaris and Linux but has moved over to Windows in the past couple of years. It is funded by angels and funds including Best Funds, Axis Investment Fund, BDC Venture Capital and Growth Works.

There are no direct competitors, but virtualization rivals include Microsoft, rPath, VMware, and Citrix. The company has about 35 employees.