Mostly on Drudge. I really do not remember any other sites. I get a lot of Vonage popups.
OK, I refreshed Drudge probably 25-30 times. Firefox said it blocked popups and let through some banners which is normal.
I'm concerned you may have something else causing the popups.
All of this becomes MOOT if you simply get admuncher. Http://www.admuncher.com. If nothing else, you can use it for 1 month for free. Try it :). 30 days of ad free life is a good thing. I support the cow, and I gain nothing from future sales, but it's probably one of the few shareware programs you'll ever run across that's worth the $25 bucks.