When I downloaded a copy of my Facebook data last week, I didn’t expect to see much. My profile is sparse, I rarely post anything on the site, and I seldom click on ads. (I’m what some call a Facebook “lurker.”) But when I opened my file, it was like opening Pandora’s box. With a few clicks, I learned that about 500 advertisers — many that I had never heard of, like Bad Dad, a motorcycle parts store, and Space Jesus, an electronica band — had my contact information, which could include my email address, phone number and full name....