I LOVE iPhone. It comes everywhere with me. It shows me movies when I am bored, finds petrol stations when I am running on empty, lets me contact my friends and family and it is a brilliant piece of technology for learning languages.
Here are some of my favourite apps for Japanese:
Touchcards 2 is a study tool that can import flashcards from Quizlet, StudyStack, and more.
iKana touch will make learning hiragana and katakana much easier and more fun!