I own two decks of Tarot cards.
I hasten to explain, before I have to (in the words of a friend of mine) turn in my Skeptic Badge, that these cards combine being a relic of the credulousness of my Foolish and Misspent Youth with a pure love of the artistry of the cards. They're beautiful, especially my Art Nouveau deck, whose images remind me of one of my favorite artists, Maxfield Parrish.
A Tarot deck, for those of you not acquainted with these tools for using The Psychic Interconnectedness of Being to extract money from the gullible, is comprised of 78 cards. There 56 minor arcana, which are broken up into suits, numbers, and face cards, rather like a regular deck of playing cards, but with different suits (cups, swords, pentacles, and wands) and with an additional face card (kings, queens, knights, and pages, the last-mentioned of which corresponds to the jack of a standard card deck). There are also 22 major arcana, each of which has a name and an image -- The Magician, The Fool, The Moon, The Sun, The Coffee Maker, etc.
Okay, I made the last one up. But some of the other ones are just as weird. How about "The Falling Tower?" "The Hanged Man?" "Judgment?" This last one shows people crawling out of open graves. So I'm to be excused, I think, if I prefer the image of a Coffee Maker.
Anyhow, the whole idea is, the cards are dealt out face down in a cross-shaped affair, and then turned up one at a time and interpreted. The position of the card in the cross determines what facet of your life it applies to -- the past, the present, the future, your work life, your worries, your love life, and so on. It matters whether the card is right side up or upside down (unlike standard playing cards, these cards are not reversible).
And of course, you can't just have any old person analyze them for you. The reader has to somehow be attuned to you psychically. According to a website I looked at called The Tarot Explained, "As the reader lays down the cards they also receive ideas and impressions in their subconscious that helps them answer your question. They are not simply looking at the pictures and giving you the answers. It is through special combinations that they are able to give you the information you seek."
The problem is, there's our old friend the Dart-Thrower's Bias at work here; during readings, people are very much more likely to notice the hits and ignore the misses when they are given such "information," especially if the reader has an air of authority (which in this case might consist of flowing purple robes and a turban). Interestingly, there was a study done on Tarot readings by Itai Ivtzan and Christopher French in 2004, and test subjects were unable to tell the difference between "real" Tarot readings and readings done from cards randomly selected by a computer. Most tellingly, people who believed in Tarot divination fared worse in this test than the average background population did.
So anyhow, it looks like accuracy-wise, Tarot readings fare no better than dowsing and crystal balls and palmistry and so on. It's a shame, because the images in some decks are really quite mysterious and beautiful. Except for "Judgment." Try as I might, I'm still not into the whole open grave thing.