If you don’t mind sharing your personal info with friends on Facebook, how about sharing them with a coffee shop who offers you a free cup of coffee for simply liking their Facebook page?
It’s a bit creepy to find that complete strangers (bet you never really ever thought that your “friends” on Facebook are mostly strangers?) suddenly know where you live, went to school, work, etc.
In fact, everytime you like a Facebook page, you are sharing your personal info with the company or individual running this page and giving them the rights to share and market your personal info. Facebook does it, Google does it. So does practically every other social site. It ain’t free for no reason.
So, go set some privacy settings. For example, Google just made available a “My Activity” page to allow you to do just that. After all, do you really want all your “friends” to know what YouTube videos you’ve been watching?