I am in the midst of the Japanese 20 series here at UCSD.  It is going well but I find myself forgetting vocabulary from previous sections that are no longer used frequently.  Flashcards certainly help but the repetition becomes very boring when you keep seeing words you already know.  I came across a neat program where you can create flashcards and then quiz yourself.  The key is you can tag cards as "easy" and they won't be shown again for a long time, whereas the "hard" ones will appear more frequently until you remember them.  They also allow you to study subsets of tags so you can quickly study "body parts", "rooms in the house", etc. in preparation for exams.

The program is Anki, and you can find it here.  They probably explain how it works better than I ever could.  It is also available on the Android and iPhone.  I have been creating decks for our textbook (Yookoso!) so you don't need to create them yourself.

If you want to be able to type Katakana / Hiragana / Kanji on your windows machine, go here.  Sorry I don't use a Mac and if you use Linux I'm sure you don't need my help :)

Kanji: Book 1

Kanji: Book 2

Book 1:

Chapter 1

Chapter 2
Chapter 3
Chapter 4
Chapter 5
Chapter 6

Chapter 7

Chapter 1

Chapter 2

Chapter 3

Chapter 4