The jobs you find on craigslist, careers 2.0, monster and the like go away after a while - typically a month. One has to pay to post the ad in most cases; after their expiry, one has to pay again.

By linking to the "Careers" or "Jobs" pages at each employer's website, I'm enabling those who use my index to find all the currently-open jobs in a given location, even if no one has paid money to run a job ad.

Also, it is quite common that jobs are filled from the resumes that the hiring manager already has on-hand, without the job ever being advertised. So if you see a company you'd like to work for, definitely do apply even if they have no open positions - but also request that they keep your resume on file.

Not every company does that. But then, not every company succeeds. I expect that a significant factor in the success of some companies is their ability to fill an open job requisition in a timely way, with the best possible candidate.

If an employer waits until a position is actually open to start advertising - when they get a new project in, or the previous employee has actually left - then that unfilled position will not be generating revenue for the employer. There will also be delays that could have been avoided, had they hired from resumes that were on file.

You will reasonably object that the employer has to pay to fill a position, but in general, an employee earns his employer twice his pay. He keeps half, the other goes to the company. Some of that pays for overhead like office rental, telephone, internet and advertising but some is profit.

If you're looking for remote tech support work that's of a more advanced nature - NOT! "Click the OK button until it turns black" - apply with Luke Crawford - no obvious relation - at http://prgmr.com/

Luke's a good guy. If he can't hire you I expect he could refer you to someone who can.