Plugin with special images which opens other images onclick

Hi,

Since I do no know what to call it I’m not sure how to find it. I currently have a wordpress site already and came with a good idea which would really work four is, not knowing if such a thing exists. So I’m asking for your ideas and experiences.

The best example is this: I have an image of a city-map. That map has several areas in different colors, different neighborhoods if you wish. If a user moves (or clicks) his mouse of this map, somehow I should be able to show them a popup or something along that line that shows the type of buildings in that neighborhood. When he moves to another neighborhood, a different image should show.
Would I have to use flash or something for that? Or are their any type of plugins that could do the same?