Last week, I added a program to my Web browser that does nothing but eat cookies – the little tracking files placed on my computer as I surf the Web. The program tells me whose cookies it’s wiping out as I go from one site to another, and most of them are from websites I’ve never visited. That’s because they’re placed by third parties, who have contracted with the websites I do visit to monitor my activity and Web habits. That data is being added to any number of personal profiles of me, which I may neither see nor delete.