I've used Google Maps
and Google Earth
a lot myself.
I rermember once following Sacramento's light-rail lines with Google Maps to see how much is now double-tracked; I've done some following of other rail lines also.
Google Earth can display layers showing a variety of features; for example,
Primary Database > Places of Interest > Transportation > Rail
You do have to home in a bit to see the railroad-line mapping; the lines are black with no owner or other information shown.
Google Earth also has the ability for you to draw your own maps; you can add placemarks, lines, polygons, picture overlays, and even 3D-model objects. You can save these maps as files, and make them available for downloading in some webspace. The map format is fully documented, so you can compose a map by hand or else write a program to create a map from some collection of data, like a spreadsheet full of locations' latitudes and longitudes and descriptions.
Google Maps does have some competition. Yahoo Maps
is a bit disappointing. While Google Maps has a maximum zoom of 20, Yahoo Maps has a maximum zoom that is close to Google Maps zoom value 17. [quote=http://www.mapquest.com/
]Mapquest[/url] does a bit better, going to about 18.5 by Google standards. However, you have to do a search before you get a map in Mapquest, unlike Google Maps or Yahoo Maps.
And while Google Maps and Mapquest have zoom increasing upwards, Yahoo Maps has zoom increasing downwards, so prepare to be confused.
operates in rather cumbersome fashion, with a small image pane and an annoying pause every time you zoom or move. Its maximum zoom is a little less than Google Maps 19. Terraserver USA
is better in some ways (bigger image pane) and worse in others. Its maximum zoom is a bit less than Google Maps 16. Terraserver, both plain and USA, does have the nice feature of offering topographical maps, so you can tell what slopes a place has. The elevations are in feet, as far as I can tell; I tried homing in on Ithaca, NY and found its elevation values consistent with that. Those values are unlabeled numbers, though some of them interrupt the contours.
I finally tried out Microsoft Virtual Earth
. Its zoom controls are magnifying glasses with + and -, and not a zoom slider; its maximum zoom is a little less than Google Maps 19, but unlike Terraserver, its images are full resolution even there. MSVE also worked much like Google's, Yahoo's and Mapquest's map displayers, updating as one zooms or pans. MSVE also has "Bird's eye", which gives you high-resolution views at a slant; you rotate the view direction with the arrows below the magnifying glasses.