Apps for studying

JED for Android - GREAT English/Japanese dictionary
Weblio - dictionary, phrase dictionary
Google Translate - quick translation, kanji translation, camera translation
Study Droid - for flashcards
Kanji Study - for kanji (wait, whuuuut?)

For the full deets as to why I'm recommending these apps, see the 7 recommended apps blog post.

Textbooks and materials

Coming soon to a blog near you...