Banners that directly interact with a known site's layout, are very effective at grabbing attention of visitors, especially repeat visitors to daily visit sites (as long as it doesn't restrict their browsing too much).

Ads of this kind absolutely need to be of the highest production values in order to impress even the most jaded of surfers, rather than simply annoy them. Giving media house 'click through' results even the quickest of glances, it is clear in the internet world, size is as fundamental as motion, to get people clicking.

Often these banners are fleeting, up only for a day or so sometimes, but they are effective enough to grab attention even within these short periods of time. The downside is they are hard to post links to, so here's one great example. From apple, for an iSomethingorother in little video form.




Note: As you can see, the page loads as the banner runs. It's also fully functional even when it is running.