Job boards on blogs won’t work for everyone but they can be both a good income earner and something that adds value in it’s own right to a blog.
They seem to work best on sites with a technology edge at present but I could see other sites with jobs that relate to their topic being possibilities also.
Traffic is a key however both in attracting advertisers as well as attracting readers to apply for jobs.
My own experience with ProBlogger’s job boards has been worthwhile. It continues to tick over with new jobs for bloggers. We don’t do quite the quantities of jobs that other boards are doing but focus in on a narrower niche and have still managed 9 new jobs across a number of topics in the last week.