I may be misusing the term a little. Not sure.
I'll explain as well as I can something that I think is Cool.
Imagine you have a graph of infinite size in a plane. Those are tedious
to display, because they require monitors of infinite size, which can
get expensive. The nodes are all roughly equidistant from their neighbors
and roughly the same in size (not that it really matters).
Now imagine you have a fat convex lens that you can pass over this plane.
The node you hover over will be centered and will be the largest one. As
you look off in any direction, the nodes are smaller and closer together.
As you approach the boundary of the lens, you're approaching infinity.
Like that Escher print with the angels and the demons, or one of the
variants thereof.
As you move the lens, a different node comes into focus. It is now the
largest and most central, and it is still surrounded by a potentially
infinite number of nodes.
There have been applets and even browsers made which worked this way.
You could "drag" nodes offcenter into focus. To travel toward infinity,
just keep dragging. And so on.
The StarTree example at inxight.com is a fairly good one. I think they
have a demo or something.
As for what I want it for: Well, it's premature. But I'd like to have an
interface like that as an alternative interface for Tycho.