No More Popup Ads. This site provides a series of links to opt out of many popup ads.
I consider popup ads the scourge of the internet. Besides the general annoyance, they can change the size of your default browser window. Many browsers will set the default window size when you close a window, so after closing one of those annoying ads, you’ll often find the next browser window you open the same size as that ad window, rather than a more reasonable size.