I love Topo! maps. As for large-scale image, though, I'm probably not the only one who tried to click on the numbers and wondered why it did something different than I'd been led to expect. It would help if you deleted the A tag from around the big image. Or, an image map would be ideal: clicking on part of the big map would bring you to the corresponding zoomed-in map. See the FAQ for how to do that in HTML.