Just wondering what applications people are using on their iPhone/iPod touch for studying Japanese.
I bought the dictionary named Japanese (discussed on the forum already) when I first got it, and found that to be really user-friendly, responsive, and full of useful features. It has limitations, though, in that you only have your standard edict synonym equivalent style dictionary, which means it's hard to interpret abstract words, differentiate similar words, and be aware of any common structures that used the word.
Today, after a lot of browsing, I ended up buying iEijiro, which is basically an iPod conversion of the alc dictionary, which means it has all the additional usage details and example sentences that come with it! For example, if you look up 想像, you're presented with the regular edict result, but if you press the 'more' button, you get all this. It's invaluable for understanding how the word is used.
iEijiro is half the price of Japanese as well, so I'd definitely recommend checking it out! The only downfall really is that it's a massive 177MB, but you'll soon see why after looking at some of the example sentences (some of which contain links to the full source presented bilingually).
Since the books come under the app store, I should mention that there are a few manga available as well. I have a few from 猫ラーメン, アップルシード, and Dominion Tank Police (not sure of the four Japanese title, but try searching for ドミニオン).