As you probably know by now there are LOTS of job boards online. But if you are going to start one now I think you are better off going after a micro-niche job site. Let me explain.
Rather than focusing on a general industry, think about breaking that industry down into subsets.
Lets use healthcare as as example. There are dozens of health related job boards that try to be the national health care job board. But what if you took it to a new level. Healthcare is a broad term. It has many facets and subsectors. There is Nursing > Travel Nursing and even LPNs. There are doctors > physician assistants. There are Radiologist, OT, Physical Therapists, etc. Why not create a site around these “micro-niches”. I think they would have a better chance at naking money rather than just a comprehensive healthcare site which has already been tried.
Micro-niche sites also have a better chance at being found in search engines because they focus on a more specific set of keywords. You could even add a location twist to these sites by adding a city or state to it such as;
You get the idea. There is traffic in these niches. And by utilizing software like Jobboard.io or SmartJobBoard you can make money on postings, backfill and Google Adsense. You could even create several of these sites to form a network of states or cities.