Technically, this should be able to help us "Walk across America", but I've yet to figure out how it works.

http://www.gmap-pedometer.com/

I played with it a little. You need to zoom in to the level you want (street, region, country) and choose a location to "jump to." Then you click "Start recording" and double-click on each point you want to include in your route. After the first point, you will see the total distance change each time you add a point.

I printed out the "Basic Usage" window and will study it.
Last year I just added up the mileage everyone reported and plotted it on a map to find where we were.