In the recruitment business, it is NOT uncommon for the head-hunters to post phantom jobs. When the resumes roll-in, they are used to build-up their data-bases. Should an attractive resume percolate to the surface or if a call is made to the search firm: "Oh, that was pulled by the client" OR "It was just filled".
In the systems integration business (computers & professional services), it is extremely difficult to find good SRs. So, whenever one of the suppliers sent an email to their channel partners (neglecting to "BCC" the address list), I would compose a professional intro and send it to everyone on the list.
If this appeals be prepared to have the principals of these organizations to come down hard on your efforts. In fairness, I had a number call me to offer me a job expressing much appreciation for my "ballsy approach".
Be prepared when you see competitors teetering on Chapter 11 as this presents itself as a superb opportunity.
I have used the job boards (workopolis & Monster) with little success. As well, I am on LinkedIn but I find these "networking" boards to be cumbersome. Where, I'v'e had some people contact me, there hasn't been much substance.
In point of fact, all-in it's probably less expensive to negotiate a good rate with a search firm (by the time you take into account the lost opportunity of having the SR generating sales earlier).
Good luck & Good selling!
Pat