I first saw this floating shelf idea on Etsy. What a great way to display cookbooks, but the price was a little too rich for my blood. Not too much later, I came across a tutorial for them over at MayDecember. I love the idea of using L brackets--so simple, so brilliant.
I loved everything about this idea except the fact that the book would show if you looked underneath the shelf. Since I'm placing my shelf fairly high up on the wall, I used a big hardback cookbook that I rarely (and now never) use, slid it into the bracket, and used clear packaging tape to tape the book shut.