- Astrology. The Golden Dawn and other esoteric organizations found that with a tiny bit of wiggling, Tarot corresponds to astrology and makes a pretty excellent teaching tool. The Celestial Tarot talks about those direct associations, and has some really gorgeous art to help you learn a little about Tarot and the stars.
- Crystals and Herbs. Magickal types love associations, so I'm going to give you a two-for-one here. The Crystal Tarot links Tarot to gemstone therapy, and if you want to learn herbcraft, there's a Tarot for that too.
- Fairy Tales and Myths. Modern Tarot interpretations are all about archetypes, and there are some universal archetypes - and some that change based on the time and nation of the telling. Fairy tales? Here, have two decks with tales from all over the world. Religion and mythology? (To be inclusive, let's say one man's myth is another man's gospel.) Arthurian, Celtic, Christian, Greek, Egyptian, Norse, even a well-researched deck about several Native American tribes, the Tarot runs the gamut.
- Recipes. There are two different decks that create recipes based on the cards, one with just the Major Arcana and one with 78 different recipes for an entire deck. And as a bonus? A deck that tells the entire history of chocolate. I'm pretty sure that's something I never knew I always wanted.
- Science. I'm pretty useless when it comes to science and math, but the Quantum Tarot somehow combines Tarot with quantum physics, and that is pretty damn awesome.
Did I leave out any of your favorites? Anything on the same subject with better research? Leave me a comment, I'd love to hear from you!