Think you will have some 'easteregg' worlds that aren't visible from the spawn, but still easily visible from at least one other world?
If I can think of something interesting enough for an easter egg I'll include some.
You could extend it to be a webbed network of worlds, even, to make it more interesting. The spawn world may not be visible but at least one other world is.
That could work, but is still less than ideal. What would be really cool is a GUI-map that uses a prefabricated image and moves the image around relative to your position. If that were made, I could place all of the worlds much farther apart.
On an unrelated note; does anyone know how to turn off the fog?