Here at Accent on Books we try to keep the shelves arranged as orderly as possible so that we -- and our customers -- can find what we're looking for. It's more difficult than you might imagine -- alphabetical by author is the "default" arrangement, but sometimes that's just not practical.
But what about at home? In a recent article in The Guardian, Sarah Crown and John Crace tackled this question, with Crown declaring, "Alphebetisation is the most banal approach to bookshelving going; who wants their living room to look like a lending library?" She also makes the legitimate point that every time you add a new book you may have to do massive rearrangements in order to preserve the alphabetical order. (If you've just bought a book by Dickens, what if there's no room on the "D" shelf?)
So, what are the other options? Most of the ones that Crown and Crace suggest seem to be based on impressing visitors, which seems to me as banal as the alphabet. I do like the method used by one of Crace's colleagues who "orders her books according to which authors would be friends in real life." Last fall here at the store, the tyranny of the alphabet for a while produced the opposite result in our Current Events section: we had books by Keith Olbermann and Bill O'Reilly shelved next to each other, with Barack Obama looking nervously on a few more books down the shelf.