Two points of relevance:<p>1. Say I walk into a shop and they can't help me, so they suggest that I go another shop down the road. When I go into the second shop, I <i>always</i> tell them that the first sent me. It's not an invasion of privacy at all and I think it's common courtesy.<p>So I don't understand why a search engine referral to a website is any different.<p>What I do worry about is what the target website does in terms of behavioral tracking, which is a bit creepy. Merely transferring referral info and letting websites use that in aggregate so they can understand their traffic better is something is not that creepy.<p>2. Google Webmaster Tools recently started showing keyword ranking and traffic data. If you study the data they share in WMT vs Google Analytics, a few patterns emerge. In a way, they are taking away the data Analytics shows and then give it back in WM Tools. This is one area to keep an eye on.