More than 57.2 million job seekers visit job placement sites each month, according to a Forbes report about the best ways to find a job. The three most popular sites include CareerBuilder.com, Yahoo! HotJobs, and Monster.com. Although these sites have been around for more than a decade, a number of other sites have cropped up, stealing the market share from the top three.

Other job placement sites such as Simply Hired, Indeed, Snagajob.com, and Beyond.com gather postings from other job sites and reorganize them to make them easier to surf.

“Many corporate companies post job openings on their own corporate Web sites, so aggregators knock out the necessity to go around from site to site targeting specific companies,” says Chuck Schilling, research director at Nielsen.

Certainly the rotten economy is driving demand for more job sites. But there’s a heavy psychological component at work here, too. Newer sites carry “the shiny-and-new syndrome,” says Lorne Epstein, recruiting expert and author of You’re Hired! Interview Skills to Get the Job, so even if another site does the same thing, there is a hope that a newer site will do it better.

Job seekers also use government job sites to search for employment. The two top government websites are USAJOBS.gov and GovernmentJobs.com. These sites attract 2.8 million and 1 million visitors a month, respectively.