The UKRecruiter has an interesting thread trashing job boards:
...I'm becoming increasing jaded towards the job boards we're using at the moment - in fact most of my candidates are coming to me from networking and referrals rather than anything else at the moment.
I share those sentiments based on our latest round of hiring at TempWorks in which I relied on a few job boards to help bring in candidates. Resume spam and artificial profile refreshes rendered the boards time-consuming and almost useless except as a general research tool.
I'll take an internal referral anytime, and some of my best hires ever came from professional recruiters.