I was listening to this podcast on mixergy with the founder of Lookcraft. In it he talks about how he markets his company with a lot of great email and landing page tips. I think a lot of what he says can be applied to job board use.
For instance with landing pages he says that the page has to be singularly focused on getting the user to convert. He mentions several sites such as Amazon and others that will not put a link back to the homepage on any landing page. This actually increases conversion rates since the user CANT click out of the page (other than clicking back button). Pretty smart.
I would suggest trying this on your POST A JOB pages to get more employers to finish their posting.
And speaking of the post a job link, you should put that thing in multiple places on your site, and always have at least one link to it from any page throughout the site. Why? Well you want to make it easy as hell for an employer to post jobs. Thats how you make money so you would do well to make it clearly visible above the fold on your pages. Dont make them hunt for it!
And when it comes to your email marketing you should also keep it simple. Less text! People dont read so keep your messages short and sweet! But listen to that interview and you’ll get some great marketing advice. I just hope you remember to employ it.