One way to get into job boards is by first starting a blog and then adding a job board component later. There are many popular examples of this. TechCrunch has a job board (powered by Personforce), so does Mashable (Jobamatic) and Marketing Pilgrim (Jobthread).
Even a blog about blogs has job listings. Pro Blogger has been around for a number of years. I was listening to a recent podcast where the person being interviewed mentioned that they posted a freelance writer position on that site for about $50 and got 50-60 applicants. That’s an awesome response rate for a niche site of that nature.
When you build a community around a particular topic like the examples above you have an automatic, targeted audience to drive traffic to job listings. Its easy money!
At the recent ERE expo I attended in Florida I learned that book publisher Wiley is starting several niche job boards to compliment their online presence. They worked with UK provider Madgex to launch some very nice looking job boards. I heard they spent close to half a million dollars getting these boards online. Madgex is the most expensive job board software provider in the world. But their sites offer the nicest design/usability.
Wiley is in an enviable position. Since they already have tons of traffic to wiley.com they can just turn on the job board switch and start reaping in the job posting dollars. Most of their new sites revolve around the healthcare and academic sectors. I think it will bring them a sizable revenue source for years to come.
http://www.wileyjobnetwork.com/
TIP: look for small industry blogs to buy and add a job board to them like Jobamatic. You can probably spend as little as $1,000 to acquire a niche blog on marketplaces like flippa.