Our favorite flashcards were passed on to us from another family on the DS journey. They are awesome because of their large size and the sign language pictures on the back of each card!
I don't see them on Amazon, but they are at babysignlanguage.com. This is the reference book from the same brand:
Our other favorites are:
Evie also loves treating this Eric Carle matching game as flash cards (they make a great gift!). She is working on learning to make pairs to match the animal pictures.
Happy flash carding, and Happy long weekend!