When you choose a web page link while using WebTV, you are sometimes presented with a banner-like ad while the new page is fetched. If you choose the ad, you're redirected to the ad's page, if not you continue to the new page as you originally intended.

I think this is a rather nice and unintrusive way to advertise, since I wouldn't otherwise be doing anything else while waiting for a page to load. Of course, this is taking advantage of a latency that I'd prefer to avoid in the first place...