Tribal Fusion is probably the biggest internet advertising company, so they are everywhere
We do use them, but we have a cap so you should only get one or two per browser session. As long as you stay on the site, you shouldn't get anymore after that. I usually get one and that's it, but I stay here all day
The Tribal Fusion popunders are what pay for this site. The regular ads only cover about 20 to 30% of costs and the popunders cover the rest. We offer an ad-free version of the forum, if it's something you might be interested in. A 6 month subscription is $15