People can do that kind of online targeting without the need for privacy invasion. For example, if I wanted to target Apple users who probably have some disposa

People can do that kind of online targeting without the need for privacy invasion. For example, if I wanted to target Apple users who probably have some disposable income, I'd buy an ad slot on John Gruber's blog. If I wanted to advertise to frequent travellers, I'd advertise on FlyerTalk. That kind of thing.