I regularly post such items when they come across my email or I become aware of them otherwise.  A lot of what I post is related to non-profit, academic, or the government sector (including international organizations).  These items are usually sorted below the blog entries that I write about substantive issues and thus come further down on the front page.  The easier way to view these opportunities postings is to click on the “Jobs and Other Opportunities” link at the top of the blog page.