With qualified job candidates in short supply, the hiring process is perhaps more important now than ever before. Yet although company builders are desperate for good workers, the cost of a bad hire is intolerable. So these days, many smart companies are developing their own idiosyncratic interview questions tailored specifically to their organization's culture.

Jim Sheward, CEO of Fiberlink, a $10 million Internet-consulting company in Blue Bell, Pa., places a lot of stock in his staff's integrity. So his favorite question to ask interviewees is, What's the biggest career mistake you've made so far? Sheward looks for reflective candidates who have learned from their errors. "I've found that those who can't think of anything either don't take risks or aren't telling me the truth," he says.

Of course, some questions are just plain practical. Tired of making offers to folks who had already accepted other offers, Eric Schechter, CEO of Great American Events, a $3 million event-marketing and merchandising company in Scottsdale, Ariz., started asking, Who else are you interviewing with, and how close are you to accepting an offer? And some questions simply make sense for certain pools of candidates. Greg Conigliaro, president of Conigliaro Industries in Framingham, Mass., says he hires a lot of prerelease prisoners, as well as convicts who have recently been paroled, to work in his $1.6-million recycling-services company. One of the questions Conigliaro asks? Naturally, it's, What were you in for?

Here's a sampling of what other company builders ask -- and why.

John Discerni, CEO, Physicians Formulary International, an $11 million wholesale pharmaceutical company in Phoenix.

    What he asks: What's the last book you read?

    Why: Discerni says that it's not what they read so much as the amount of time it takes for them to answer the question: if they have to think a long time, they probably aren't that well read.

Tony Petrucciani, CEO, Single Source Systems, a $5.1 million systems integration company in Fishers, Ind.

    What he asks: Why do they make manhole covers round?

    Why: "We ask this of potential developers to see if they get flustered, and how they think on their feet," says Petrucciani. (The answer? Because covers of any other simple geometric shape could fall through.)

Robert Baden, CEO and president, Rochester Software Associates, a $4.3 million software developer in Rochester, N.Y.

    What he asks: If I stood you next to a skyscraper and gave you a barometer, how could you figure out how tall the building was?

    Why: The answer: well, there really isn't one. Baden just wants to see how creative people are. According to company lore, one interviewee responded that he'd find the building's janitor and then offer the janitor the barometer -- in exchange for information about the building's height.

Doug Chapiewsky, CEO, CenterPoint Solutions, a $2 million software developer in Denver.

    What he asks: If you had your own company, what would it do?

    Why: "I want to see if they've got that certain entrepreneurial spirit it takes to succeed in a small software company," he says.

Madonna Flanders, employment manager, Community Health and Counseling Services, a mental-health and home-health-services company with more than 1,000 employees, based in Bangor, Maine.

    What she asks: If I asked your previous coworkers for key words to describe you, what would they say? Then if I leaned close and whispered, "Now tell me what I'd better watch out for," what would they say?

    Why: To find out how in touch candidates are with their own strengths and weaknesses. "I also get information that I can check with references when I call," says Flanders.