This two are good. I would try to find bloggers (followerwonk) writing about books, and ask them to leave a review about their favorite book at this store. It should be simple to get a nice scale.
Next step can be organize contest for best book review. Books as awards, and best reviews you can use as deafult to that product.
If some new ideas will come to my mind, i'll let you know! 
btw: this is good topic for brainstorm.
