Re: Facebook and Amazon book question
I stopped using my facebook page a long time ago, FB is dodgy to the core. These days I'd be wary of every single app, so many of them are designed to exploit your account for advertising or to hack it even.
A married friend of mine ended up a member of a dating partner site she had never ever visited, because an app passed on all her profile details to the partner site without her knowing. Now she can't get rid of it because she doesn't have access to the dating site's member page because she wasn't the one who made the account. Had to just block the emails and try remove all trace from her FB page, but that doesn't stop the site from sending out her profile to single men around the world. Dodgy...
Just yesterday I saw two friends accounts get hacked and porn advertisements put on their wall.
I also remember a conversation that was leaked between the creator of FB and one of his staff members where he bragged about all these private details he had access to about millions of people. Not sure of the legitimacy of that story though.
So long story short, be very wary of every app and connection other websites make to FB - but Amazon should be safe enough. In their case I go with the general consensus, it's to get free advertising out of you.