It's old news that job searchers like to make connections online to increase their odds of getting the right job. What some job hunters may not know is that recruiters are looking at those connections too, long before the interview process begins.

In fact, a survey of 3,100 employers by CareerBuilder.com shows that use of social networking sites to research candidates has grown from 11 percent in 2006 to 22 percent in 2008. Another 9 percent said they plan to start using them to screen candidates.

Of the recruiters who used social networking profiles to screen candidates, one-third said they eliminated a candidate based on what they found. Top concerns were: information about drinking or drug use (41 percent), provocative or inappropriate photos (40 percent), poor communication skills (29 percent), and a candidate bad-mouthing a previous employer or a current co-worker (28 percent).

Gail, a recruiter at a Fortune 500 company, told an editor at CareerBuilder.com that she found racial slurs and jokes on a social networking site of a potential hire. "And there was yet another instance where a candidate told me he was currently working for a company, yet he left a comment on a friend's profile about how it 'sucked' to be laid off, and how much fun it was to be unemployed!"

The world of online social networking, at sites like MySpace and Facebook, can be a small one, and first impressions can be formed in a moment. It's important to remember that all your online information may be viewed by a recruiter or interviewer, so you should either post only content that would not be objectionable to an employer, or set your profile to "private" so that it can be viewed only by friends of your choosing. A "block comments" feature may also be helpful so you can have some control over what people say on your site.

Another piece of advice from CareerBuilder.com is to regularly scan your online records to see what's out there. If you find something potentially harmful, see about getting it removed.

LinkedIn has been an important tool for searchers and recruiters alike. Company co-founder Konstantin Guericke told National Public Radio that users can make the rules.

"We have a setting when you sign up for the site that says, Are you open to being contacted about job opportunities?" Guericke says. "And a fairly large percentage of the user base checks that. It doesn't mean they are now actively looking for a job. I think they are just being realistic. There is virtually, for everyone, there is a job that maybe pays more, is closer to your home, with a more prestigious company." More than 130,000 recruiters are on LinkedIn. Spoke, Jigsaw and Ryze are other business networking sites.

A common mistake people make is letting their networking skills slip, even though some experts estimate more than 60 percent of job seekers find new positions that way, the Boston Globe reported. Make sure to update your profile with the latest information on current and past roles, titles, names of employers, responsibilities, skills, technologies, certifications, awards and degrees. These are the areas most often searched by hiring companies and recruiters.

A columnist for Search Engine Watch.com predicts that social media will change people's behavior offline. "The openness of social media can often have drastic consequences in relation to jobs, relationships, etc.," writes Erik Qualman. "People will start leading their lives as if their mother is watching." When it comes to job searches, maybe that's a good thing.