Currently there are a few of these items available. My personal take on them is as follows:

iChing created by astrology.com is very nicely done. The information well and appealing presented. The only drawback is that at times it seems a bit a hit and miss to touch the rotating ying/yang symbols to make them stop and this gives the feeling of being just a tad off in time, but it is a visual ‘trap’ - it does register the tap instantly but takes a moment then to come to a halt.

Touch Tarot created by TouchTarot@me.com is interesting for the single cards reading, it allows to browse them or pick one randomly and also has the Celtic Cross. What I do not like about this application is that one is not able to choose to have reversed cards in the reading or not, it forces them onto you and there is no way to turn them off. I know that the views split on this issue, some want reversed cards, myself I tend to the other path and work with uprights only.

iTarot is another application created by astrology.com and gives a simple 2 cards option: daily tarot and love tarot. The meaning of the cards are written in the “I” form - something which you might like, but it feels forced to me - it gives a strong feeling of “self suggesting thoughts” (like a mantra) and this is not what I feel is the quality of tarot. But this one is fun entertainment.

All of these applications are for free and can be downloaded from the iTunes store for the iPhone.