Facebook Login now working again!
Issues related with being able to log in using your facebook account onto this site, have been fixed. Feel free to log in again, and link another backup account for access in the future.
Linking a new account is easy, and you can access it right from your user preferences:
Sorry about the inconvenience, but it was something on Facebook's side, they decided to change the way they handle 3rd party login and failed to notify everyone properly.