Kinokuniya is a Japanese bookstore that specializes in new and rare magazines and books. They actually air items in from Japan! Go visit their flagship store across from Bryant Park.
This store has many great art and fashion books, as well as fun Japanese cultural books, anime, and all sorts of curious odds and ends.
My two most recent purchases were a book in the Japanese culture section about useless inventions, and a denim themed issue of Lightning magazine (very hard to find in USA).
Maybe one day I'll learn Japanese...