Here's an edited Google Map of the Narita area:
And, here's Jetstar's Narita Layover Google Maps page:
View a larger version of the above Narita Layover Map in a new window with the points of interest labeled and described.
Here's a link to a very large file (1.3MB) which is a scan of a recent Narita tourist map. Best to just download this rather than viewing in your browser: Narita Tourist Map