What are these strange numbers scattered around the site?

They are National Grid References. They each identify a bit of land (or sea) 100m square. The Skye Guide links these references to an Ordnance Survey map, where an arrow in the centre of the map is the point to which the text refers. You can then zoom out to see a wider area. For example, NG640038 is the grid reference for the ferry terminal at Armadale.

More information on how to use the grid is here .