Rather than a map that can zoom in to the finest detail, I think that if you want this type of effect, it would be better to produce a map that is hyperlinked to sub-maps that show proportionally smaller and smaller areas. This is done really well at numerous sites on the internet (though I can't remember any off of the top of my head). This form of "interactive" map achieves what I think you are trying to do while eliminating the drawbacks already mentioned above.