Listed alphabetically:
♣ Art and Symbols of the Occult by James Wasserman
I initially disregarded this as just an art book. While it is that, a great deal of information has been packed into the text that you'll be hard-pressed to find compiled in any one source. The sections on Kabbalah, Alchemy, and Tarot have been particularly useful. Did I mention the pretty pictures?
♣ The Chicken Qabalah by Lon Milo Duquette
One of the first books that made the Tarot feel completely accessible to me, this collection of work by Duquette's fictional(?) Rabbi Lamed Ben Clifford slays you (or tries) with broad humor, but that sugar is just the coating to a very potent pill. This book succinctly presents the very backbone of western mysticism in plain speech, then sketches out applications in the tarot and other practices.
♣ The Complete Book of Tarot Reversals by Mary K. Greer
Most card readers don't bother treating upside-down cards any differently (memorizing them right-side-up is daunting enough) but for those who are ready to inject an extra layer of meaning into readings, Greer's book is an excellent leaping-off point. Though with perhaps not quite enough new information to warrant a whole book, this is actually a pretty good basic guide for all readers, heavily padded with lots of inspiring ideas about reversals.
♣ Complete Illustrated Guide to Tarot by Lynn Pollack
This book was given to me secondhand, and I was prepared to dismiss it as another hopelessly general book full of pointless do's and dont's. To my surprise,it's an incredibly thorough introduction written by someone with a quick mind and a wide knowledge. Not particularly instructive when it comes to spreads and actual card manipulation, but overall a great Tarot reference book.
♣ The Game of Life by Timothy Leary
Kudos to anyone who can finish this book. I never did, but the first two thirds broke down a lot of brain-barriers and got me thinking about the Tarot on new terms. A sort of comic "workbook" for humans attempting rapid evolution, Crazy Uncle Timmy arranges the Major Arcana into a schematic to chart your progress.
♣ The I Ching or Book of Changes by Wilhelm/Baynes
The most thorough and readable book I've found so far on the I Ching (which I'm just now finally beginning to learn).
♣ Keywords for the Crowley Tarot by Hajo Bahnzaf and Brigitte Theler
The Thoth deck's symbolism may match this book's descriptions a little more closely, but it still offers myriad interpretations per card, all laid out in neat tables for quick reference. As an introduction to the Tarot, this book is resourceful, creative, honest, and concise, and will have you reading in no time.
♣ The Kybalion by Three Adepts
First published in 1908, this book influenced many 20th century religious and psychological movements. It's essentially a catechism of seven principles by which a person can learn to fully govern his or her mental states. Interesting as an artifact, inspiring if you can get over the archaic terms, and certainly useful alongside any discipline or practice you may be working on.
♣ Liber Null and Psychonaut by Peter J. Carroll
This primer of Chaos Magicians may have fallen out of favor a tad since it was written decades ago, but the first part, Liber MMM, is as basic and efficient a guide to meditation and the beginnings of modern individualistic magical practices. While you might not dig the hooplah about aeonics and so forth that follow, it's well written and interesting, and makes for great conspicuous subway reading.
♣ Man and His Symbols by Carl G. Jung
While Jung only wrote the titular essay, his colleagues and contemporaries present plenty of equally relevant material, making this a terrific reminder that Jung was an entire movement just as much as he was merely a man. A survey of Jung's work is especially important to understanding how a Tarot reading effects us, both during and afterward.
♣ Promethea by Alan Moore
This 5 book graphic novel works overtime to illustrate (literally) the beautiful essence of Kabbalah, Tarot, Tantra, and mythology. It's also perhaps the most insightful meditation on the Apocalypse that this generation may receive (and considering literary tastes at the moment, that's really saying something). As a superheroine and a living myth, Promethea walks between worlds easily-- will she tear ours down in the process?
♣ The Tarot of Ceremonial Magick by Lon Milo Duquette
No matter how silly and inviting Duquette's colored-pencil illustrations are, this book is NOT for beginners. In fact, it's downright esoteric and may be only of remote interest to you unless you approach the Tarot as part of a magical tradition. However, Duquette's ideas and good humor continue to blaze, making this a rewarding and challenging read that will test your commitment to whatever personal beliefs you may hold.
♣ The Western Mysteries by David Allen Hulse
This book is probably just bathroom reading to people who speak a million languages and have p.h. D's in religion, but for everyday folks like me, it's an impenetrable wall of information with keys to the mystical traditions of every conceivable Western Civilization. However, it has a great section on Tarot, and every now and then I'm able to find the answer to some really obscure question in it-- and it looks fantastic on a bookshelf, so I can't recommend this enough. Pick up The Eastern Mysteries too, if you have the upper-body strength.