The web mapping site 192.com has a very nice map zoom control which dynamically displays a representative image of the map at the prospective zoom level.
This nicely addresses a problem which has occurred in a few applications I've been involved with recently - how to communicate to the user what a given zoom level actually looks like.
At first I thought the control might be truly dynamic - i.e. pulling a live tile from the centre point of the current map view. But it's actually just a set of tile snippets at a fixed point. Still, it provides a very nice effect. (The dynamic version would be simple to implement, but perhaps would be too slow in actual use, with unpredicatable latency).
Are you listening, OpenLayers?