I know this tool has been around for a while, but...One has to wonder about the boldness of G to allow all this data to be accessed by the public. If the site runs analytics it shows the aggregate data, if not it shows "estimated traffic". Also, it shows visitor retention, clicks on site, time on site, and average visits per visitor.
http://www.google.com/adplanner/Info available:
Content Categories
Description
Advertising accepted: yes/no
Daily Unique Visitors estimated or via Analytics
Unique visitors estimated cookies/users
Reach
Total visits
Avg visits per visitor
Avg time on site
Sites also visited
Audience Interests
There is also a bunch of ad specific data...
It may not be the "secret sauce", but its damn revealing of what they have at their disposal.
