so recently i tweeted on the "bird site" about something interesting i noticed on the facebook landing page - if you're logged out, the site's js will check to see if your browser filled in an autofill / autocomplete username, and if so, sends it back to facebook, presumably for tracking reasons.
this kinda pissed me off, since i've had a deleted facebook account forever, but have (as any normal internet user will be forced to do) gone to facebook links. they really got me this time!