In reply to Lurking Dave:
it depends. If you consider that whatever you put online in theory can be viewed by someone else and you decide you're not bothered about someone seeing your wedding photos then there's no problem. I put photos up online and don't care if someone sees them. I would however be wary of putting any evidence of committing a crime (such as taking drugs, though I don't do anyway, not my thing) in case someone I didn't want to see them did. Same for rants such as about work with trackable details.
but there's a lot of people that seem to think along the lines of "I once looked at a news site, the CIA must know everything about me, have read every word I've ever put in an email, care, and will be on the way now to kidnap me!"
...or at least somehow force you to buy products you didn't want. It seems that's a big one, "oh no advertising will be targeted to me!". Guess what, it always was, it's just done so a bit more accurately that it used to be. You still don't need to buy anything you don't want to.