Web annoyance

There are some web pages where, no matter which part of the page you navigate to, the annoying ad in the sidebar follows you. You scroll up, you scroll down, you think you have lost the bugger, but no, the ad always catches up with you, notwithstanding the fact that it ends up wheezing and panting in the process.

You are basically not in control. You have no power over it. You can block the ad, of course, but nothing can be done if it is an integral part of the page, like Google Groups' Go to the top feature. That leaves you feeling hopping mad. Which is certainly not the state of mind the advertiser wants you to be in when you are looking at his product...