JobThread :
It offers both a free standalone widget that provides job opportunities related to your site and a free comprehensive job board tool.
WebJobs :
webJobs is a job board program with a price tag, but it might be within your budget depending on the features you need.
WPJobBoard WordPress Plugin :
If you use the self-hosted WordPress.org blogging application, then the premium WPJobBoard plugin might be a good option for your job board.