By Olga Kharif, Bloomberg Businessweek

In his more than 15 years as a headhunter, Jeff Vijungco has tried Monster, Craigslist, CareerBuilder and other online job boards. Lately the head of recruitment at Adobe Systems (ADBE) has scrapped most of them.

"I think job postings are such old news," Vijungco says. "Social is the hot new industry."

Recruiters are filling openings faster by relying on new tools that scour social networks and target workers who aren't necessarily looking for jobs. 

LinkedIn (LNKD), the biggest professional-network​ing website, got into the field early with the introduction of Recruiter in 2008. The service lets headhunters search its more than 187 million profiles and contact potential candidates.

Since last year, Adobe has found more than half its new hires through LinkedIn. Adobe, the biggest graphic-design software company, uses job boards to fill only about 5% of openings.

In 2011, LinkedIn introduced additional features, including Talent Pipeline, which enables recruiters to track and stay in touch with candidates. The Mountain View, Calif., company held 5% of the $5.4 billion online-recruitment market in 2011, double its share the previous year, according to researcher Outsell.

LinkedIn's online-recruitment division generated $138.4 million in the third quarter of 2012, 55% of its total revenue. It charges companies $8,000 a year for one to two users of Recruiter, while headhunting firms usually charge about 20% of a new hire's annual salary.

Potential candidates' views and interests

Two-thirds of companies already use Facebook (FB), the world's largest social-networking service, to find recruits using the site's friend-finding search function, according to a June survey of more than 1,000 human resources professionals by recruiting software maker Jobvite. Fifty-four percent use micro-blogging service Twitter to learn about potential candidates' views and interests, the survey found.

Facebook last month debuted a social jobs application that aggregates more than 1.7 million job listings from Monster Worldwide (MWW) and other sites and lets members share them with friends.

The next challenge is to develop advanced tools that find greater detail on candidates from more social networks, says Brian O'Malley, a general partner at Battery Ventures. His firm has invested in social job-search startup Entelo, which trawls Twitter, Google's (GOOG) Google+ and other sites, using proprietary algorithms to find candidates for specific positions and predict who among them may be open to offers.

For instance, when Twitter users change their location on their profiles, it may be a sign that they've moved and will be looking for a job. Entelo debuted in October and says it already has more than 50 corporate customers.

Another startup that uses Facebook profiles, BranchOut, has raised $49 million from investors including Accel Partners and Mayfield Fund. Its app lets people search for jobs using their list of Facebook friends and their friends' connections, and to post videos and photos showcasing their career achievements to a profile.

Next year, BranchOut will start charging recruiters a subscription fee for searching its database, which has 30 million registered users.

Year-old startup TalentBin says it has more than 100 corporate clients that pay $6,000 annually per internal recruiter to scour sites, including Meetup, Pinterest and the U.S. patent database, to find qualified tech workers.

Secret developers

"No good software engineer puts his resume on Monster, because then they get 10 to 20 e-mails a day from recruiters," says Elliott Garms, a recruiter at Groupon (GRPN). "Really good developers try to hide. TalentBin allows me to identify people I might not have even seen."

Traditional online job boards have been under more pressure to go social. Last year, Monster.com -- which reported a 10% decline in revenue from continuing operations in the first nine months of 2012 and is looking for a buyer -- introduced BeKnown. It helps job seekers find positions through Facebook connections, and invites colleagues to connect professionally and earn badges and endorsements.

"Monster has evolved far beyond the traditional job board model," says Tom Chevalier, the New York company's strategic marketing director.

CareerBuilder also has a Facebook referral app, Work@, which lets workers share their company's open positions with their friends.

"We think that every major job board player is going to be looking at social data," Entelo co-founder Jon Bischke says. "A lot of them are seeing what's happening with LinkedIn and trying to figure out how they can compete."

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