I mentioned yesterday that content was king. The more you have, the more you publish in your niche, the more SEO traffic you will get.
Check out these job boards and how they approach content:
http://www.collegerecruiter.com/blog/
http://www.snagajob.com/resources/find-jobs/
The sites above write content that is relevant, timely and interesting. Your job board should do the same.
When I started GreenJobSpider.com one of the best ways I got content easy was asking professionals in the green industry to answer an email Q&A which I then published word-for-word as a blog post. Boom! Instant content. (see example). Google loves content like this. Their search engine eats it for breakfast.
To get content I would also consider hiring a career coach (just search twitter to find hundreds of them). Pay ’em $20 per post and you’ll get some timely articles from career experts.