The arrangement helps Bazzarvoice keep its internal IT staff down to only two of its 200 employees.

"Our internal IT is working on only a handful of things, such as keeping people's personal machines up and running,'' Maag says.

In April, Bazaarvoice announced that it has served more than 10 billion user-generated reviews. The company launched its service in January 2006.

"We'll probably be at least doubling again in the next year'' in terms of the number of servers it rents from Rackspace, Maag adds. He says he is considering migrating Bazaarvoice's Exchange e-mail service to Rackspace, too.

Another company that plans to increase its use of outsourced data centers is Wall Street Systems, which uses Savvis for its corporate network infrastructure and to support its software-as-a-service offering. Wall Street Systems provides treasury and high-performance transaction-processing software to financial institutions.

"We're using Savvis' utility computing framework to deliver our solutions to our clients,'' says Mark Tirschwell, chief technology officer of Wall Street Systems. "We've probably tripled the amount of infrastructure that we had a year ago from Savvis. . . . We were originally using some shared Savvis components, firewalls and things like that, but now we have our own dedicated firewalls and our own dedicated Active Directory infrastructure all managed by Savvis.''

Wall Street Systems uses Savvis as its corporate network and to provide e-mail, videoconferencing, voice over IP and standard data communications to its 500 employees in 12 countries.

But it is seeing more significant growth in its use of Savvis' data centers to support its software-as-a-service offering. Wall Street Systems uses two Savvis data centers now, but it expects to add two data centers in Europe during the next year.

"We expect continued growth at the levels we have been seeing,'' Tirschwell says. "This is great for us and good for Savvis, too. We see the market for our products expanding even in this shrinking economy. As more companies become very conscious of costs . . . the software-as-a-service value proposition is stronger.''