Re: Well you know...
. . . also make sure your friends and family aren't on any of them either. I don't know about you, but most of my friends are on it and they share photos with me in them and talk about me. No, I'm not narcissistic - I don't mean they talk about me non-stop - just that my name, likeness and contact details are all in there.
Likewise, Linked-in has my details because numerous people (ex-colleagues, clients, etc...) have put them in to send invitations. News sites, property sites, jobs boards, online stores - anything that allows you to forward content to other people - they all have contact details for people who don't actually use their sites.
Sure it's nothing compared with what people put up about themselves but no thickness of foil hat, save when constructed while living in a cave in Tibet, can prevent information about you and your activities finding its way on line.
I would say it's time for me to take the foil off but it's comfy and I've got hat-hair now.