I was reading the cams v bolts thread and although I'm firmly in the non bolt camp on that score, it got me thinking....
I've been climbing on a few crags this year that used essential metal belay stakes hammered into the turf above the crag as there wasn't anything else.
But on reflection, there was often rock, in the form of big partially buried boulders [ie, wouldn't take a sling round them]. Perhaps bolts on these would have been safer and better longer term? Most stakes I have used have had some degree of wobble and so presumably need re-locating sooner or later.