I just launched Weekenjobhunt.com that targets weekend only job listings. I started it because it had only 1 legit competitor jobsweekend.net and the category gets over 200,000 monthly searches. Now there are two boards that target this niche and I believe over time I can get on the first page of google for this phrase. Early results are promising. After just a few weeks its picking up long-tail searches. All I did was add a couple of backlinks from some of my blog properties. The site is a custom design based off the Jobamatic API.
So I did a little more digging and found that there are a few other niches like weekend jobs to target.
Night Jobs (201,000 global monthly searches)
Evening Jobs (135,000 global monthly searches)
Part-time jobs (2.7 million monthly searches)
I believe if you start a board that targets any of these niches you will make money and get traffic. Regarding part-time jobs there is really only 1 major site Snagajob.com. If you google that phrase there are just a bunch of other general sites getting love from google. Partimejobs.org is on the 2nd page of results and its a totally crappy site. I think this niche has some potential if you can build an SEO friendly site that targets the long tail.
Night jobs is an interesting niche too. Competitors include: Workatnight.com but its just a crappy looking jobamatic clone. ‘Evening jobs’ is similar. There are NO real job boards in this space. So if you went out and purchased Webjobs or Smartjobboard or Jobtarget you would make money over time. Just register a keyword rich url like EveningjobsHQ.com or Nightjobsnow.com.
These are free ideas for new boards that I only share with premium members. Take them if you wish.
And good luck.