This photo from Superhero is taken in a San Francisco bookstore where an artist named Chris Cobb rearranged all 20,000 books by color. Not sure if this helped the owner sell more books, but it looks pretty cool. Read more here. The photo is part of flickr's Rainbow of Books pool. Take a look to decide if you want to do this in your own house. I don't think I could stand not being able to find my books, but my friend did it a year or so ago, and it looks nice at her place.