What America's most interesting companies have in common.

These commonalities help to explain why many other innovative and successful companies—Yahoo (YHOO), Whole Foods (WFMI), and Microsoft (MSFT), for instance—don't make the SAGA cut at the moment. Yahoo hasn't changed anything about American life; Whole Foods is a presence in upscale life but has yet to achieve the mindshare of a Starbucks; Microsoft is no longer characterized by a strong sense of purpose. There are a few other companies that we think of as potential SAGA contenders. One is Netflix (NFLX), whose SAGA status will probably depend on how it adapts its business to the age of digital downloads. Another is Facebook. Its explosive growth and deep engagement suggest SAGA-like passion, but it is still relatively young and occupies a space that is vulnerable to fads.

Of course, SAGA companies themselves aren't invulnerable. Each has gone through a crisis. Indeed, with the exception of Apple, each might now be plausibly said to be going through a slump (as Apple did in the mid-'90s). Both Starbucks and Apple had to bring founders back in to run the companies after investors and even many customers lost faith with corporate leadership. Starbucks' plan for global growth has stalled and may never be realized; Google has been criticized for failing to develop and integrate the companies it has gobbled up in recent years. But it's the ability to admit shortcomings and to retool the corporation that sets the SAGA companies apart. Even when they're going through tough times, they're still the companies we want to read about.