Hi xorpion and welcome, I write ViewingDale which is purpose designed to do that zoom job. It doesn't have "levels" as such. It zooms through an infinite hierarchy which you can edit using the app. We run the CWBP here - the community world building project where we have many maps at various stages of scale and resolutions and I have combined them all into the one zoom world using it. You can see a you tube vid of that here:
https://www.youtube.com/watch?v=qELcbKXdRm8

You can do something similar with other applications. I think Fractal Mapper might have similar zoom capability. You can also prerender the whole map in high res into tiles and put them into a tile based web server app like GeoServer or WorldWind etc. The only issue there is that its hard to modify any part of the map without re-rendering the composite as a whole and redoing the tiles.

Anyway, if your interested then the link is in my sig for the website. Theres a few tutorials and other resources on this site which you can get with a search or a look at the keyword index - also in my sig.