Our house has a lot of books - books in cupboards, books on the floor, books in the kitchen (cookbooks, mostly) and even a few books on shelves. The photo above is one of six actual proper bookcases in our house, and probably the neatest, but still, "Bookcase Showcase" seems a rather hopeful title. As you can tell from the photo, my bookcases are sadly nowhere near showcases; this one is more a sort of mix of stationary cupboard, games compendium and whatnot. I was tempted to tidy up before photographing but I heroically resisted, so this is the unvarnished version.
The books are crammed in a bit too tightly to allow much clutter on the shelves themselves, so it has all congregated on the top of the bookcase. On the left is a stack of boardgames, plus a bingo set I got given for Christmas, a sword and a top hat (what self-respecting household doesn't have a sword and a top hat on their bookcase?) and a box of firelighters. On the right is a wooden boat my dad made for my oldest son the Christmas before last. Also a small blue suitcase full of bullets (not real ones, obviously. Nerf gun bullets).
Underneath are the books. I'm not sure what a psychologist would be able to tell from my books, apart from the fact that I work in publishing and have extremely catholic tastes. On the top shelf Nancy Mitford and Rumer Godden rub shoulders with JM Coetzee, Thomas Hardy and Don Quixote (full discloser: I have not actually read the latter - though I keep meaning to.) Below Sarah Waters is nestled up against Peter Ackroyd and on the left is my reference section - a mix of dictionaries, language books (Brewer's Phrase and Fable, the Concise Oxford, The Cambridge Companion to Old English Literature) and classic texts (the Complete Shakespeare, Malory's Morte D'Arthur). Lots of these I borrowed from for the Winter Trilogy but I also have another reference section upstairs with the books I'm currently using for writing, more handily located for my laptop, and they swap back and forth. At the moment the upstairs shelf is mainly books on Victorian domestic history, plus a fabulous book called "Carriages at Eight" about the history of the horse-drawn carriage in Victorian and Edwardian England.
The system is... chaotic, to put it kindly. The grouping is partly thematic but mainly done according to size, which might seem like a purely cosmetic thing, but is actually because I double stack all my books (as you may already have spotted) and this only really works if you have similar sized books grouped together otherwise they don't fit - so the largest hardbacks have to be paired up with the little B format paperbacks, and the larger A-format paperbacks go next to smaller format hardbacks.
Here you can see a little glimpse of the secret half of my collection - the unseen books lurking behind. The top of this photo shows part of my crime/thriller collection nestling behind what was the Oxford Dictionary of Quotations - I have a great weakness for 1930s and 40s classic crime, here you can see Agatha Christie, Dorothy L Sayers, Ian Fleming and - for some reason - my dad's ancient 1970s paperback of How to be Topp. I did say the system was a little chaotic. Below is a shelf of little hardbacks so they have the bigger A format paperbacks behind - Laura Ingalls Wilder's Farmer Boy, The Tempest... various others. There is no grouping in this particular bit, although I do have a cupboard of the books I owned as a child upstairs - Laura Ingalls Wilder probably belongs there, but it's not, because I bought this particular copy quite recently.
There are obvious disadvantages to shelving this way, namely I spend an inordinate amount of time searching for particular books. I was recently trying to find John le Carré's The Spy Who Came in from the Cold for a friend and I just couldn't. In the end she left without it - and weeks later I came across it while looking for Flambards Divided by KM Peyton. But the double-stacking system avoids the alternative, which is throwing books away. We recently moved house and I did sacrifice ten boxes of books that I just couldn't bear to cart across from one flat to another - but these are the ones that made the cut, so I can't get rid of them. Even so, there are a lot that I probably don't need. Jade of Destiny for example by Jeffery Farnol (tucked in next to On Chesil Beach, second from the bottom) I have never read and probably never will - but it's got the most fabulous 1950s cover, and who could resist that title?