I went into my privacy settings on facebook to turn off the "instant personalization" program (I don't really want facebook to provide my info to other sites automatically), and was a little miffed by the experience of disabling it:
First, I unchecked the box that said "Allow select partners to instantly personalize their features with my public information when I first arrive on their websites." This was me reverting backwards towards previous policies facebook had back when it was not sharing data with third party sites.
Anyway, when I checked the box, I got the usual "are you sure?" dialog that attempted to convince me to reconsider. In addition, it let me know that checking the box won't completely opt me out, since my friends will still be leaking my information to these third party sites.