So far, only Google does, because they place good quality targeted ads that people are actually interested in. Trying other advertisers, you may see ads coming and going, I am avoiding images or anything that does not integrate well with the site. No popups will be placed, if you ever see a popup, let me know or check if it's some other site that made popup. I personally hate popups.
FEAR ME! (or dont i couldnt care less) 