What is the latest trend in website design?

I don't know what they call it, but it is extremely annoying. It is popup ads within the page. It is like a deck of cards being fluttered in your face. You have to search out the little 'x' to get rid of it. The 'x' can be anywhere, and sometimes it moves when the cursor gets near. Youtube flicks have them at random times and places and you miss most of the flick while you are trying to opt out. Amazon.com has a big one at the bottom of every page and if you close it, you get another one with every new page.