Google Books privacy concerns
Google Books has instituted a feature called 'Bookshelves.' Any book you have in your library will be placed on the 'Favorites' bookshelf automatically, and you can also place your books on various ones such as 'Read', 'Not read', etc, and others of your own designations.
What they don't tell you upfront is that your bookshelves are Public, can be viewed by others through your Google profile unless you opt out.
I don't have anything there I'd care if people know about, but I turned privacy on out of general principles. While I realize that 'sharing' and 'social networking' are the hot new buzzwords, I'm aghast at Google for sharing my stuff without my permission in the first place.
'Private' should be the default, not 'Public.'