Jobstart works with job seekers to help them get hired, and gets paid when their recruiting clients hire their candidates. Sometimes Jobstart's candidates get jobs at non-clients, and Jobstart doesn't get paid. Jobstart can help negotiate offers, for which they charge the candidate 20% of the difference between original and accepted offer. I'm an independent agency recruiter, and it sounds a lot like what I do. I don…
One thing recruiters are useful for is that usually have a list of interview questions their past candidates got from each company. But usually this list is not as comprehensive as even just careercup or glassdoor.
But every company I have worked at had an internal wiki of interview questions and guidelines for evaluation. The number of questions is usually very small and study-able. With just the knowledge of my company's current wiki (and some past experience as the interviewer) I am pretty confident I can train even the weakest of candidates to pass the interview.
Probably due to legal or ethical reasons though, I haven't seen anyone try to collect these database of questions from each company. Is it that risky to ask your candidates to leak them to you after they get hired?