Almost all shrines and temple have a stamp which can be collected in a stamp book. From what I understand, in old Japan people would need proof and permission to travel so the monks would have to get the shrine/temple stamps as proof of where they had traveled. Now-a-days it offers a unique kanji and symbol of each shrine/temple. I often use them as stamps in the picture I am taking in that area, for pilgrimages or of the shrine/temple.