About a year ago I decided to release the articles on one of my small sites into the public domain. I did this because the articles provide information about a certain social cause, information which I want people to see. So I put a notice on the home page saying that all the articles on the site have been released into the public domain, and that anyone may copy and republish them for any purpose.
Since then, One article has been scraped and republished at least 10 times and most of the others at least once. What surprises me is that the scraper usually includes a link back to the original page on my site, even though in my notice I didn't request a link back.
During this time the site's rankings have improved and overall traffic has steadily increased, probably because of the new backlinks
I realize there is a risk that a copy might eventually get a higher ranking in the SERPs than the original page, but so far that hasn't happened.
Obviously this approach is only suitable for certain types of sites and not for everyone.