The Case: In 1999, when former Oracle executive Marc Benioff founded Salesforce.com, companies bought software and ran it on their  computers. The idea of handing  customer data to another company and then renting access to software running on its servers sounded insane. But today, "software as a service" is a viable business led by Salesforce, whose best early decision disappointed many customers.

You may have noticed that you're spending less time lately using the software you purchased for your PC and more time using websites that offer the functionality of traditional software. For instance, if you manage your e-mail using Gmail, Yahoo Mail, or Microsoft's Hotmail, or you've used Google Maps (see "Killer Maps" in this issue), then you're part of a trend roiling the software industry: "software as a service."