Facebook's new Anonymous Login option.
This solves a common problem with Facebook apps or logins, where maybe an app looks interesting, but a user doesn’t want to share a bunch of data up front. This way there can be a trial while a user forms an opinion about an app, then go back and adjust preferences later if they want to share more information.
Adjusting that information is also going to get easier with the new options in Facebook Login. Controls are more granular now, there is an option for “Edit the info you provide” and the data listed there can be adjusted by the user, including whether or not it will post to Facebook.
These new options will be rolling out across Facebook in the coming months.