I'm beginning to like it, even though I can't think of a real example I'm "fired" (ho ho I'm so funny) to do a bit of research.
Would they have to be open to the public? - even if only periodically or by appointment. Otherwise, as haggeus says you could get some pretty anonymous buildings with a sign outside saying "Blacksmith" (or "kovar" or "forgeron", "seppä" etc)
Bonus points for a picture of the anvil. Double dare bonus for a picture of your GPSr on the anvil.
Agree with Bean Team's point about non permanent waymarks by the way. Also, any category that's not inherently visitable will come in for some criticism and "nay" votes at peer review. (Believe me)