As discussed in the NYT article, Allegiant's business model is small and beautiful -- rather than focusing on popular routes between major cities like most startup airlines, Allegiant serves a web of routes going to just two destinations.
In this map, the two destinations are clearly labeled; all the originating cities are marked with those serving both Las Vegas and Orlando highlighted. Extra information is provided through shading of the States served, and through the route lines (roughly indicating distance / time).
This simple chart can be made simpler by removing the route lines. Not much is lost by removing them.
Reference: "Flying Where Big Airlines Aren't", New York Times, Sep 21 2006.