I've been Bambi-eyed into sharing this link, and for the record I should have thought of posting it here myself! Anyway, Yale University has a collection of bookplates numbering approximately 1 million, and
some of them are on display and they are so AWESOME. Especially the fifteenth century one. And the one where the owner is beheading a delinquent borrower. Oh, to be the curator of this collection!
I also have some shaped children's books but have not had a moment free to scan and share. Hopefully this weekend.