At MayDecember Home, invisible shelves are made using the same L-brackets as the other how-to's we've seen. However, there's one simple difference: the brackets aren't screwed into a book to create the shelf, the brackets are the shelf. Sure, this means you can see the brackets if you get down and look from the underside. But that's the price you pay to prevent destroying a book!
What do you think, is it worth it to save a book? Or would you destroy a book (albeit one that's obsolete) to be sure the brackets don't show?