Giving new Web services and apps your social login data makes them more useful and personal, and some new ones won’t even let you register unless you connect Facebook, Twitter or LinkedIn.
But there’s no great way to keep track of all that sharing, and it is far too easy for a service to misuse access to highly personal information like the identity of your family and significant other, your birthday, your photos, even your friends’ religious and political views. Once you click yes on that little dialog permission box, you probably never think about it again.