I surf several sites.
This is what I had experienced on more than 1 website.
This only happened after Facebook IPO.
I had already "Liked" the websites long ago.
But sometime after the Facebook IPO, each time I surf a website, there is a pop up window.
Another variation is a pop up window to remind me that I and several others "Like" this website.
I had to click on the X to close the pop up screen.
This is repeated on every page or screen I change to, within the website.
The window keeps popping up.
This is becoming NASTY.
The number of Likes may show how popular a website is.
The number of Likes may reflect how pervasive Facebook is on the Internet - and thus may increase its power to ask advertisers for more money.