If you live in the US and inform the US Postal Service that you are moving to a new location, it invariably happens that you will receive a Welcome packet from USPS at your new address. Guess what the packet contains? Apart from the regular USPS stuff, you will see coupons from Home Depot and other neighborhood stores. How did they come to know that you were moving? Of course the USPS told them. Or they already provide coupons to USPS to place in the welcome packet. I prefer the latter to be the case.
Now, let me give you another instance. You go to ToysRUs or any other store, you will be asked, "Can I have your phone number?". You either will meekly tell them or ask them as to why they need it. The response will be that it is to send marketing material (coupons etc). I am sure that they are quite concerned that we do not receive enough junk mail and the USPS needs to justify a post man for your street. :)
The November 12th issue of Information Week has an excellent article on Privacy Vs. Personalization: Can Advertisers Ward Off Looming Threat Of Do Not Track List.
The summary is:
It's time to give consumers a say over all that data being collecting on them. Otherwise, a Do Not Track list--or worse--could be in the future.
Mathew Ingram writes a nice article on "Facebook’s No-Pseudonym Policy Is Short-Sighted", in which he quotes a NewYorker cartoon
In the early days of the Web, about 15 years ago, The New Yorker ran a now legendary cartoon in which two dogs are sitting in front of a computer, and one is saying to the other, “On the Internet, no one knows you’re a dog.”
Google's social networking site, Orkut has an interesting feature that tells you who viewed your profiles recently. Well, this is clearly a violation of trust that an user has, when he registers with Orkut. Now how do I ensure that people do not know that I checked their profiles.
Look at this Business Week article on "Looming Online Security Threats in 2008"
Web-based services, including social networks MySpace and Facebook, are becoming prime targets for hackers seeking your personal information