Lawrence calls the service "horizontal-type advertising." He sees Monster.com as a "life improvement" Web site that could provide a variety of tools for schools that want to reach potential students. If a job seeker is looking for sales jobs, but might not have the required MBA, Monster could serve a related ad to the job candidate from the University of Phoenix promoting classes or degrees, for example.

Lawrence says the ad-serving technology relies on behavioral targeting to present job seekers ads across Monster's sites, alliances and partner networks, including eBay, Comcast and Microsoft. The company already uses it to serve ads related to open jobs.

The technology, which launched in 2007, ties into Monster's jobs database. "The behavior that Monster is tracking is job search behavior, which includes the jobs people click on and apply for," he says. "We follow search behavior on Monster.com and related sites to serve up dynamic ads."

The behavior is completely career-focused, but Lawrence says the information could be leveraged long-term for other types of advertising. "We estimate having cookies on about 20% of the general online population," he says. "The ad tags are out there, similar to other ad tags, but all the ads today are configured to show relevant jobs to a job seeker."

Monster.com's technology lets companies turn their recruitment message into standard Interactive Advertising Bureau ad units. The technology pulls out key components from the job, such as the targeting attributes from the job posting. When companies posts a job on Monster they choose its physical location, category, and career experience and education level required.

The ad network takes the targeting attributes and transforms the job into an ad. It syndicates it on the Career Ad Network and uses the attributes to target people looking for jobs. A cookie from Monster dropped on the person's computer looks for the job to make the match.

On sites similar to eBay, Monster.com will serve up ads using Akamai IP targeting based on geographic area if the company can't find a Monster site cookie on the person's computer.

A September comScore Media Metrix report for the most visited ad networks rates the Monster Career Ad Network at No. 25. Reaching an estimated 84 million unique people, Monster Career Ad Network touches about 43% of the U.S. online audience.

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