Getting a job ain't easy nowadays. With the official unemployment rate above 8%, there are millions of people still looking for work, creating a very difficult, competitive environment. Many staffing companies are helping the unemployed throughout the job process, and thriving as a result. Human resources is evolving quickly, and if you want to invest in this area you should know who's doing it well and who's not. 

Making interviews happen
Getting a face-to-face is perhaps the most important part of the job-hunting process. Which companies are bringing the most value to consumers in this regard? Five companies are considered below.

Three winners
Most people know about LinkedIn (NYSE: LNKD), the premier professional social networking tool. As more people join the site to seek work, more employers come to the site to recruit, which attracts still more job-seekers, and so on.

The stock currently trades at more than twice its $45 IPO price, and is one of the few prominent Internet companies that has gone public recently and actually done well. And it's no wonder why: EPS growth this year is up almost 250% from a year earlier, and the company recently had a blowout quarter.

Paychex (Nasdaq: PAYX), which, as one may expect, provides payroll services in addition to its human resources arm, has done very well in the past year -- its stock has climbed more than 35%. Some of its performance may be owed to its prodigious dividend, which stands at a staggering 3.9%.

The company also benefits from high margins; gross margins are three times higher than the industry average at 75%, and net margins are more than 12 times the industry's. Fool blogger Christopher French points out that this is largely due to Paychex's beneficial cost structure and scalability -- it doesn't cost a whole lot to process checks for new clients. And although HR services accounted for nearly $600 million in revenue in 2011, Paychex derives most of its revenues from its payroll services, so it's nice to see efficiency here.

2011 HR revenues accounted for just under 30% of annual sales, but they grew 10% from the prior year, which was five times as fast as the company's payroll services segment.

As long as unemployment continues to slowly trend lower, this business should see steady measured growth and could even be a hedge against future inflation.

On Assignment (Nasdaq: ASGN) provides permanent and temporary professional staffing services internationally, with a focus on life sciences. From chemists to microbiologists to lab assistants, On Assignment is the go-to place for highly skilled scientific professionals.

Though it's smaller than some of its competitors, its niche has allowed it to specialize, and the company has reaped the benefits from its narrower scope. Earnings this year were more than four times last year's, and Q2 sales were up almost 100% from the second quarter of 2011. With almost 1 in 4 shares owned by insiders, shareholders can sleep easy knowing that management's interests are aligned with their own.

And a couple of losers
Part of the reason LinkedIn, Paychex, and On Assignment have done well is because they've differentiated themselves. Each company does at least one thing very well, ensuring that competition will have a tough time moving in.

Not true with Monster Worldwide (NYSE: MWW), which competes with a myriad of other online jobs websites like CareerBuilder, LinkUp, and CoolWorks. Although Monster can be useful for the unemployed, this company is a total dog -- and, as we can deduce from its name, a three-headed one at that. Its revenues have steadily trended downward for the past five years, while its EPS decline in the last year has been a much more violent ride for the investor, falling by more than half. Roller coasters are bad enough, but imagine one that never stops going down.

Kforce (Nasdaq: KFRC) is a small-cap staffing company with operations in the U.S. Nowadays companies want to test out employees before committing to bring them on full-time, and the growing demand for temporary workers is the X factor that drives Kforce's industry. With the percentage of temps in the workforce approaching all-time highs at nearly 2%, you'd think Kforce is well-positioned for the future.

Unfortunately, Kforce has decided to follow in the footsteps of Monster. The two companies announced a partnership in July, and Monster will now be powering Kforce's recruitment portal. If relying on Monster to power its platform isn't enough to make investors squeamish already, Kforce hasn't differentiated itself, either. It faces stiff competition from much larger companies with wider networks of employers and job-hunters. Its 10-K states that "there are 98 staffing firms with more than $100 million in U.S. staffing revenues." Perhaps that's why it lost $33 million in the most recent quarter.

Put your money to work!
All five of the companies above assist the consumer in the employment-search process, although only three look like they can assist investors. Still, until we start to see some serious changes in the job market, this industry looks like it'll continue to grow.

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