One these by Robin Wood (is there a Little John in the house?) who is a leading light of the English Heritage Crafts Association. The article contains a little vignette on how natural Grindstones (the good old Carboniferous Millstone Grit) have been used to make walls in Sheffield, UK. Read Robin's Article here.
I also like the fact that Mike (and I suspect I know which Mike) in the comments refers to a chuch in Tacony, PA which is built with reshaped grindstones from Disston and Sons the saw and tool makers.
What a wonderful way to share and propagate knowledge.