Niche sites controlled about 64% of the online job-search market in 2006, up from 39% in 2004, according to Gordon Borrell, chief executive officer of consultancy Borrell Associates. The rivalry will only accelerate this year, as demand for online recruitment surges. A recent HotJobs.com survey indicates 40% of workers plan to look for a different job in 2008. Much of that searching will happen online.

The Big Three have the most to lose. In the past six months, visits to Monster, HotJobs, and CareerBuilder dropped by 23.7%, 18.4%, and 7.1%, respectively, according to Hitwise. "The generalist site is falling away to that very strong niche," says Borrell.

Sure, you may be thinking that job boards have been absorbed left and right by larger boards, but let's face it: more keep appearing and the growth is not slowing down. No question, the use of niche-specific job boards has grown, so now the question remains whether -- and for how long -- general job boards can remain effective.