well, assuming your using the filmer pack, if you set one keyframe at say, 24mm zoom and then one after at 75mm zoom, as you go on in the timeline, the camera just keeps zooming and you can get it up to a 500mm zoom. Or go the other way and get it down to a 10mm which looks a lot like a fisheye (most complain it looks wierd though and like to keep it around 15mm). Anyways, the big zoom is where it's at.
Here's a video that kind of explains it better in terms of how to get the fisheye look, but it works for both ways: