I'm only a student, so take my words with a grain of salt.
I don't mean to advertise for StackOverflow, but it struck me that an their job board would be the biggest competitor to a potential HN job board.
I find that jobs.stackoverflow.com is clean and seems to have consistently interesting postings. On the other hand, I'm not sure how many conversions they get, and the UI is rather basic.
They've also recently launched careers.stackoverflow.com, which integrates with StackOverflow accounts. The theory is that employers can scope out an applicant's know-how by glancing at his reputation and postings.
Anyway, as someone seeking employment, I echo your interest in finding a good solution. Good post.