Job interviews rank up there with root canal for most people. Wouldn't you want to know in advance the trickiest question your prospective employer might ask on your job interview?In today's recession, where competition for jobs is fierce, the interview experience is even more stressful. So, feeling better prepared can help.

The folks at career site Glassdoor.com realize this and have launched a new service to help job seekers deal with the dreaded interview process.

Glassdoor.com's new "Job Interview Questions and Reviews" section features feedback from actual job applicants who completed job interviews at about 1,000 companies in a range of sectors--including technology employers like Google and Yahoo-- over the last 18 months or so.

Till now, Glassdoor.com focused mostly on providing salary data about specific job titles at employers, as well as insights about what it's like to work at these companies. Over the last two years, Glassdoor.com has collected from its members more than 200,000 salary reports and reviews about the working environments of 22,000 employers in 100 countries. Many of them are technology employers.

Now Glassdoor.com is offering up reviews and tips related to what it's like to interview for jobs at many of those employers.

Glassdoor.com compiles its information from its visitors. But before you're allowed to gain free access to the job and pay information shared by other Glassdoor.com visitors about their employers, you're requested to anonymously post information about your own salary and employer.

For a limited time, Glassdoor.com is providing "first click free" access to visitors who want to check out a review about an employer without having to provide info about their own pay or employer.

Glassdoor.com isn't out to trash employers , but it's not about publishing "puff piece" reviews about companies, either, says Glassdoor.com co-founder and CEO Robert Hohman, who was previously president of Hotwire, the discount travel site of Expedia.

In its reviews of employers, Glassdoor.com asks visitors about "the pros and cons" of working at their companies. "It's not a ranting or complaining site," he says. "About 15% of content gets rejected, the reviews need to be even-handed," he says.

In a private beta project, Glassdoor.com recently began collecting information about the job interview experiences of visitors to its site, he says. "There's enormous fear around job interviews," he says. "Job interviews are one of the most stressful experiences, especially now in this economy with so much competition for jobs," he says.

Based on the feedback Glassdoor.com has gotten from job seekers so far, the most difficult technology-related companies to interview with include Google, Amazon and McKinsey, he says. Some job seekers tell Glassdoor.com there seemed to be an extra level arrogance they encountered during interviews at those companies, he says.

On the other hand, many job seekers had good impressions about Cisco and PricewaterhouseCoopers even when they didn't land jobs there, he says.

Reading the job interview reviews of others is "like being a fly on the wall" to see what the experience might be like when it's your turn, so that you're better prepared, says Hohman.

Some of the technology companies ask job inteview questions that test your thinking process and creativity, not just your tech knowledge, he says.

So, what are some of the oddest questions tech job seekers were asked?

Here's one of them:

"Given 100 white marbles and 100 black marbles and two jars, put these marbles in the two jars in a way that would maximize the chance of retrieving a white marble from any given jar."

As you're figuring out how you'd answer this one, tell us about the hardest or weirdest questions you were asked on a job interview.