Ads taking over the screen

i just got some ad that basically fills up the center of the screen and scrolls with the page if you try and scroll away. a close button was there, but was very small and hard to see, since it used the same color font as the copy for the forums. i'm sure this has been brought up before, and i know you're just trying to make some extra cash by selling ads (so i don't use adblock on this site), but can do you guys screen what ads get published so that we at least see relevant, non-intrusive advertising?