Should We Have More Open Cookies?

Should We Have More Open Cookies?
Cookies store information about us and our surfing habits (and they are yummy). One of the secure things about a cookie is that you can only access it within the web site to which the cookie belongs.

So if you are visiting www.kinlane.com I can put a cookie on your computer, but only I can access it. I own the domain www.kinlane.com

I just watched a movie on a famous band on Netflix. After watching I went to Youtube to look up more videos on this band.

Before I could watch my video on Youtube, I had to watch an advertisement trying to sell me Netflix.

It seems like we should have a "header" or part of a cookie that any domain can read. So youtube.com could query netflix.com on my computer and see if I'm a Netflix member, or at the very least see I just came from Netflix.

Just a thought.