I made a Tarot reader for the iPhone, here's the link (launches
iTunes):
http://phobos.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=284038820&mt=8

My friend used this in the field and said it worked really well.

And here's some reviews:

From Tarotseer, "As a professional Tarot card reader for the last 44
years I feel qualified to say that this is the best application of its
kind that I have ever encountered. ... This is a great thing to have
on your iPhone and I recommend it most heartily! Bravo!"

From MadeByMarkDotCom, "the creator of the program has included a HUGE
library of spreads, making this software the most flexible, capable,
and usable Tarot application for the iPhone, period. Frankly? It
leaves iTarot and Touch Tarot in the dust. If you are going to buy one
Tarot app for your iPhone, make it this one. That's an opinion, by the
way, from a Tarot author and deck designer, with more than a decade of
experience reading with and writing about the cards! with Tarot on
your iPhone, you'll always have access to a Tarot deck ... and you'll
have one more reason to pull out that shiny, sexy iPhone in public!"