Clic Bookstore & Gallery in NYC is one of my favorite spots to stop by when in NYC. I completely lose track of time looking at the exhibits and flipping through their gorgeous books.
One show that really made a lasting impact on me was James and Karla Murray's, entitled "Storefront." It featured old neon signs from around the city. For some reason, I've always been slightly obsessed with these signs, and the book accompanying the exhibit is amazing.