Google Earth has heights
Note that this is Google Earth (requires the installation of an application), not Google Maps the web site.
I notice some discussions of the availability of topographical maps. While I am not aware that Google Earth can be made to easily display topographical maps with countour lines, it does have a constant reading of terrain elevation on the bottom of the display. I have checked a couple of places in the UK and they seem is good accord with Ordinance Survey maps. Google is about 1-2metres greater than OS in the two places I checked. Could be different reference point is in use.
e.g.
Google 26m
OS 25m
I would expect that anyone interested could determine the source of the data used.
The options allow the display to be set to feet or metres.
I would guess that a programmer could figure out how to extract a topographical map with countour lines, at least of a small area.