Privacy

Hi all:
 
I'm a journalist writing for a couple of German computermagazines, e.g.
www.emar.de <http://www.emar.de> , www.net-business.de
<http://www.net-business.de> .
At the moment I am doing some research on a story about privacy.
Do you know some sites which use the information you give them for your
advance? Amazon.com would be a good example.
I'm looking for every site where you can get the more specific information
the more you let the net know about you.
 
Thanks, josefine