I entered in some of the node.js books I have been reading into my goodreads list. And they mentioned that they were recruiting.
The programmer who told recruiters about github meet the same fate as the police officer at the end of the wicker man. But at the risk of the same thing happening to me this is a really clever idea. If you are looking for people who know about an area checking if they read the books is one way. Only goodreads can advertise on their site but anyone can look up book reviews.
The other surprising thing is with 800k followers goodreads twitter mentions must be like looking at the digital rain from the Matrix. But they noticed that I mentioned their recruitment idea and replied.