How this this work? Wouldn't the same site origin prevent it from reading cookies from other sites? I even have third party cookies disabled but it can still find a lot of cookies from other sites.
I'm guessing something like PhantomJS (other versions of QTWebKit are available) on the server - some of the samples that comes with it shows how to capture all the requests resulting from loading a URL.
If you could classify the cookies and 3rd part requests into the different functionality groups, then you'd really have a tool.
That said, 3rd party cookies are usually evil.
First Party Cookies - Third Party Cookies - Third Party Requests
Mashable: 12 - 13 - 36
Techcrunch: 12 - 37 - 30
Betabeat: 7 - 4 - 28
Apple:13 - 0 - 0
Microsoft: 4 - 3 - 3
Reddit: 5 - 0 - 5
NYTimes: 6 - 6 - 16
Khan Academy: 9 - 1 - 8
Groupon: 10 - 1 - 18