The big recruitment groups (Stackoverflow, github etc) tend to be startup/large corporates.<p>Where should smaller companies, who have different requirements advertise?
I think there are regional differences to be accounted for. NY VS SF Bay may actually be more similar then, say somewhere in alabama or ohio. And I suspect things are very different in the UK, though probably not as much as in eastern europe, south america, or asia.<p>So I think you should quantify your question. Otherwise expect a fair bit of bias based on the locality of the commenter.
LinkedIn is very resourceful for both Recruiting and Job Searching. Doesn't matter if you're looking for big or small their database is large enough to find niche markets for both the employee and employer.